Dr. Yisrael HaKohen Ziderman*

The Rediscovery of the Tekhelet Chilazon in Our Times

1. Introduction

Recently, we have witnessed a growing movement among those seeking to fulfill the mitzvah of Tekhelet in tzitzis in practice, especially in the yeshivos of Alon Shevut, Efrat, and Ma’ale Adumim. As the number of people thirsting for knowledge increases, the time has come to publish and update the findings of the research conducted since our article, “Toward the Renewal of the Mitzvah of Tekhelet in Tzitzis,” appeared in Techumin 9 in 5748 (1988).

We will present the subject in an organized form. The comprehensive work of the Chief Rabbi of Israel, Rav Yitzchak HaLevi Herzog zt”l, written in 5673 (1913), “Hebrew Porphyrology,” in The Royal Purple and the Biblical Blue (Keter, Jerusalem, 1987), will continue to illuminate our understanding of the sugya. This article is based on a lecture we delivered at the tenth-anniversary conference of the Temple Research Institute during Pesach 5754 (1994).

2. Background

We will begin by outlining the historical and intellectual chain of events that led to the rediscovery of the Tekhelet chilazon.

Two of the great rabbanim laid the foundations of the entire project. They are like the “Yachin and Boaz” supporting the effort to renew the mitzvah of Tekhelet in our time. These were the Radzyner Rebbe, Rav Gershon Chanoch Leiner zt”l, the pioneer who went before the entire camp, and, following him, the Chief Rabbi, Rav Yitzchak HaLevi Herzog zt”l.

These two great luminaries—may their zechus protect us—possessed extraordinary knowledge both in Torah and in general science. The proper combination of the two contains the key to discovering the truth, in keeping with the principle that “derech eretz precedes Torah.”

3. Rav Leiner of Radzyn

We will begin with the fascinating story of Rav Leiner, as he himself related it more than a century ago in his sefer Sefunei Temunei Chol (5647/1887):

For many years I have taken to heart the matter of the mitzvah of Tekhelet, which, because of our many aveiros, has been withheld from us…

(Sheloshes Sifrei HaTekhelet, Jerusalem, 5753, p. 4)

He continues:

After Hashem helped us clarify the identifying signs through which the chilazon may be recognized… it is a mitzvah upon anyone capable of searching for it to do so, thereby enabling Klal Yisrael to fulfill this mitzvah, which has been forgotten by the Jewish people for several hundred years. Whoever merits accomplishing this will be blessed by Hashem, the God of Israel…

I sent people to the regions of the Mediterranean Sea, and the creature was brought to me. It belongs to the species known as ink-fish [cuttlefish—Y.Z.], of which there are approximately nineteen species. It appears to me that one of them possesses all the identifying signs explained in the words of Chazal. Its blood, which is black like ink, is also in my possession. However, none of the craftsmen skilled in the process of separation [chemistry—Y.Z.] are capable of separating it.

(Ibid., p. 37)

Accordingly, we must correct the commonly repeated account that the Rebbe discovered the common cuttlefish when he arrived in Naples. He states explicitly here that “the creature” had been brought to him in Radzyn even before that.

He was therefore in Radzyn when he determined the identifying signs by which the cuttlefish was brought to him. However, none of the people he approached were able to produce a dye from the sepia, or “blood.”

In his second sefer, Ma’amar Pesil Tekhelet (5648/1888), we read:

In all the scientific books dealing with the range of colors, and in all the books of those expert in the processes of combination and separation [chemistry—Y.Z.], there is no information whatsoever about how to produce a Tekhelet color from the blood of any animal species.

(Ibid., p. 44)

That was what he believed. He thought that perhaps he would succeed if he could obtain the “chilazon” alive. Until then, only a dead cuttlefish had been brought to him in Radzyn.

We have still not seen the chilazon alive. We therefore undertook the burden of traveling great distances by sea, and we arrived at the Mediterranean coast, in the city of Naples, Italy… There, [in the underwater observatory—Y.Z.], I saw the living chilazon moving about freely…

This creature is commonly called the ink-fish, because it contains blood that is black like ink. From it they prepare a dark-brown color. It is extremely valuable and is used by artists who paint precious works of art.

(Ibid., p. 41)

Obviously, this brown color known as sepia has no connection to the dyeing process the Rebbe later developed. The use of sepia as a brown pigment in painting is an entirely different matter. It is not a textile dye used to color threads, but an oil-based paint that must be mixed with eggs and oils and then applied as a layer over the artist’s canvas.

After the Rebbe saw the living creature, he continued his account:

I began to involve myself practically in the matter, to bring this heavenly craft into the light. I traveled by sea and am presently… here in the city of Venice. After great effort, I found the chilazon on a small island at the edge of a western inlet, in sufficient quantities to gather enough of its blood for dyeing…

(Ibid., p. 202)

He then wrote:

I began to perform the work of the mitzvah with tremendous effort… With Hashem’s help, I succeeded in extracting the color of Tekhelet from the blood that is black like ink, in such a manner that nothing assists the dye except the blood of the chilazon. The other ingredients are themselves colorless and merely act to extract the color from the blood.

(Ibid., pp. 203–204)

The conclusion of the story is described in the introduction to his third sefer, Ma’amar Ein HaTekhelet (5670/1910):

With Hashem’s help, on the first day of Chanukah 5649, after many experiments and tests involving great effort, I succeeded, with Hashem’s help, in dyeing the first vat. Within a short time, several thousand Jews were wearing Tekhelet in their tzitzis…

At the beginning of 5650, I began dyeing with the blood that I had brought from its place of origin. With Hashem’s help, many thousands of Jews placed Tekhelet in their garments of tzitzis. Today, more than twelve thousand Jews have already begun wearing Tekhelet.

(Ibid., p. 29)

4. Rav Yosef Dov Soloveitchik of Brisk, the Beis HaLevi

One of the Gedolim whom the Radzyner Rebbe approached, and to whom he sent his sefarim in order to receive a haskamah or an opinion, was the Beis HaLevi, Rav Yosef Ber Soloveitchik of Brisk, who passed away in 5652 (1892).

The Beis HaLevi did not accept the Radzyner Rebbe’s discovery, for a very fundamental reason. He sent him the following letter, which was printed in the introduction to Ma’amar Ein HaTekhelet.

The Beis HaLevi ruled that it was not sufficient merely to prove that a particular chilazon fit the identifying signs given by Chazal. It first had to be established that the proposed chilazon had in fact been used for dyeing in ancient times, and that at some point in history knowledge of the chilazon had been lost.

The basic principle is one of “Renew our days as of old”—restoring what had previously existed.

The Gaavad of Brisk, Lithuania, conveyed… his refusal… in the following words:

His honor did not explain what he discovered after it had been forgotten: whether he discovered the fish itself or the method of extracting its dye. Only after his honor clarifies this—meaning that there was something that had been forgotten and he rediscovered it—will we be obligated to listen to him and wear it.

However, if we say that the fish continued to exist, and that the method of extracting its color was known throughout all the periods that passed from the time Tekhelet ceased among Klal Yisrael, and nevertheless our fathers and forefathers did not wear it, this is as if we possess a kabbalah and mesorah from our fathers that this fish and its color are not the chilazon and Tekhelet—even if it possesses all the identifying signs that Chazal gave for it. Even if we were to bring many proofs, they would be of no use against the kabbalah and mesorah.

Only after he clarifies for us that this fish, or the process of producing its color, ceased to exist and was forgotten at some point—so that the chain of kabbalah was broken—may the halachic sources serve as evidence for us. These are his words; may he live.

(Ibid., p. 13)

We see here a different conceptual approach, according to which the disappearance of Tekhelet must be understood in the following stages:

1. First, we must know with certainty that the proposed chilazon was used in ancient times for dyeing wool. We may not be able to determine today precisely which shades were produced from it, but it must be proven that it was used to dye wool.
2. Second, at some point in the past, the matter must have been “forgotten,” thereby preventing the continued fulfillment of the mitzvah of Tekhelet.
3. Third, we must have rediscovered it today, allowing us to assume that this is what existed in earlier times.
4. Only then is there reason to examine whether it fits the identifying signs given by Chazal for purposes of halachah. If one begins only with explanations of the signs, there is obviously no end to the matter, because each person can explain any particular sign differently, in his own way.

To what may this be compared? To our return to Eretz Yisrael. If we relied only upon identifying signs—the ground, rocks, water, trees, rivers, and sky—it would be difficult to prove that this country is Eretz Yisrael. Rather, we possess a clear mesorah that this is Eretz Yisrael, the place where our ancestors lived two thousand years ago. Without that, the identifying signs would have little significance.

The same is true of the chilazon. If we wish to reconstruct the practices of our ancestors, we must first rely upon the preliminary test described in stages 1–3 above.

5. Different Understandings of the Beis HaLevi’s Position

Over the years, a different interpretation of the Beis HaLevi’s position was transmitted, as may be seen from the words of Rav Yosef Dov Soloveitchik zt”l in Shiurim LeZecher Abba Mari Z”l (vol. 1, p. 228):

It is well known what took place between my grandfather, the gaon Rav Yosef Dov HaLevi, and the gaon, the Rebbe of Radzyn, concerning Tekhelet in tzitzis. The Radzyner Rebbe renewed it and instructed all his chassidim to place Tekhelet in their tzitzis.

The Rebbe attempted to prove, on the basis of many sources, that this color was truly Tekhelet. Rav Yosef Dov argued against him that proofs and logical arguments cannot establish anything in matters that depend upon mesorah, regarding which it says, “Ask your father and he will tell you.” In such matters, logical argument is not decisive; only the mesorah itself is decisive. This is what our fathers saw, this is how they conducted themselves, and this is how their children must conduct themselves.

In this spirit, on 5 Elul 5749, I received the following letter from Rav Tzvi Hershel Schachter shlita of Yeshiva University in New York:

To the honorable Dr. Ziderman,

Shalom u’vrachah.

I received the volume of Techumin as a gift last Shevat, when I was in Eretz Yisrael. I also received the reprint of your article in the mail at the time. Unfortunately, I have not yet had the opportunity to study it, and I ask your forgiveness for my delay. I am extremely occupied with my work in the yeshiva and do not have sufficient time.

I only recall hearing from my rebbe, Rav Yosef Dov HaLevi Soloveitchik—may Hashem send him a refuah sheleimah from Heaven—that he said in the name of the gaon, the Beis HaLevi—and I believe the letter was printed in the Radzyner Rebbe’s Sheloshes Sifrei HaTekhelet—that it is impossible to reconstruct a mesorah concerning an identification that has been forgotten through scientific research. I have found this point difficult for many years.

I am very interested in reading the article, and, with Hashem’s help, when time allows, I will send you my response.

With wishes for a kesivah vachasimah tovah, a year of life and peace, and much success in your holy work,

Tzvi Schachter

It should be noted that while the Beis HaLevi himself rejected relying exclusively on proofs drawn from halachic sources—that is, the identifying signs of the chilazon mentioned by Chazal—Rav Soloveitchik zt”l understood that the objection applied specifically to scientific proofs.

In my response of 3 Marcheshvan 5750 (November 2, 1989), I attempted to clarify the matter:

To Rav Tzvi Schachter shlita, New York:

Shalom u’vrachah!

I was especially pleased to receive your reply dated 5 Elul 5749, and I thank you very much for it.

Two research approaches may be described for resolving the problem of identifying the Tekhelet chilazon.

According to the first approach, we search among the creatures presently existing in the world for one that possesses the characteristics and identifying signs attributed to the Tekhelet chilazon in halachah and aggadah. This approach might have been appropriate for our ancestors leaving Mitzrayim when they were first commanded to dye Tekhelet. However, when Rav Gershon Chanoch Leiner zt”l followed this approach, he was sharply criticized by the gaon, the Beis HaLevi zt”l.

After the Rebbe requested the Beis HaLevi’s opinion concerning the introduction of the supposed “Tekhelet” in Radzyn, the reasons for his opposition to the proposed identification were transmitted, as quoted by the Rebbe in the introduction to Ma’amar Ein HaTekhelet.

Based upon these words, we can establish the preliminary conditions that must be clarified before examining a proposed identification of the Tekhelet chilazon according to the simanim.

First, there must be unequivocal proof that the proposed creature was actually used in some manner to dye wool during the period of Tanach, the Second Beis HaMikdash, and the Gemara. After all, our primary objective is to “renew our days as of old,” restoring the former practice.

Obviously, no one will come today and point with certainty to a particular creature and say that this is specifically what our ancestors used to produce Tekhelet. Nevertheless, we cannot begin identifying it according to the simanim until we are convinced beyond all doubt that the proposed creature was in fact used to dye wool during the period when the mitzvah of placing a thread of Tekhelet in tzitzis was being observed, and when Tekhelet was used in the Mishkan and the Beis HaMikdash.

If we are not one hundred percent certain that the creature in question was used for dyeing at that time, there is no place even to conduct a halachic discussion about whether it should be identified as the Tekhelet chilazon.

Once it is established that the proposed creature was in fact used for dyeing in ancient times, a second condition must be met. At the time Tekhelet disappeared, knowledge of either the identity of the dye-producing creature or the dyeing process must have been lost, and that knowledge must subsequently have been rediscovered.

If knowledge concerning the proposed creature had remained continuously known and available throughout all the intervening periods, while at the same time the authentic Tekhelet had disappeared, then according to the Beis HaLevi it is “as if we possess a kabbalah and mesorah from our fathers that this fish and its color are not the chilazon and Tekhelet, even if it possesses all the identifying signs that Chazal gave for it.”

The Beis HaLevi was aware that the common cuttlefish proposed by the Radzyner Rebbe as the Tekhelet chilazon did not satisfy these conditions, and he therefore rejected it.

Today we know with absolute certainty that there is no indication whatsoever that the common cuttlefish was used for dyeing in ancient times. Furthermore, the Chief Rabbi, Rav Yitzchak Isaac HaLevi Herzog zt”l, investigated the matter and established that the actual coloring substance produced through the Radzyn process is nothing more than an iron cyanide salt—the first synthetic pigment, known as “Prussian blue,” which was discovered in Berlin in 1704.

Prussian blue was produced by dissolving ox blood or meat in alkali and combining it with iron. Beginning in 1749, Prussian blue was used to dye wool in France. The detailed process adopted in Radzyn is identical to the known process for manufacturing Prussian blue.

From a technical standpoint, therefore, there was nothing novel in the Radzyn process. The only difference was that, instead of using ox blood or some other animal substance as one of the ingredients, they specifically used the ink of the cuttlefish.

The Radzyner Rebbe proved that it is permissible and obligatory to renew the mitzvah of a thread of Tekhelet in our time. However, he erred in identifying the chilazon.

In contrast, it is well known that the banded dye-murex, Murex trunculus, discussed in our article in Techumin, fully satisfies the conditions established by the Gaavad of Brisk for selecting a creature whose conformity with the simanim in Chazal may properly be examined.

Indeed, in that article we demonstrated the remarkable degree to which the banded dye-murex conforms to the signs given by Chazal for identifying the Tekhelet chilazon. This conclusion has already been accepted by the researchers who have worked and continue to work in the field of Tekhelet research.

With greetings of peace from Tzion,

Dr. Yisrael Ziderman

On 19 Sivan 5753 (June 8, 1993), I wrote the following letter to Rav Schachter:

Following our correspondence concerning Tekhelet four years ago, I was encouraged when you attended the lecture I delivered on the subject at the Lincoln Square Synagogue last year.

I was recently pleased to learn that a thread of Tekhelet had been ordered for you from the activists of the Keren HaTekhelet organization, and I understood that you intended to use it for the mitzvah of tzitzis.*

6. Chief Rabbi Rav Yitzchak HaLevi Herzog zt”l

Sixty years ago, Rav Herzog published his study, “Tekhelet in Israel,” a shortened Hebrew version of the above-mentioned manuscript from 5673 (1913), in the periodical HaHed. I will present two central points from that study.

First, how did Rav Herzog view the Radzyn dye, which had been invented approximately twenty years earlier?

Rav Herzog did something that was virtually unheard of in the rabbinic world at the time. In 1913, after receiving an authentic sample of a Radzyner “Tekhelet” thread in the mail, he sent it to the leading dye chemists of his generation for chemical analysis.

The analysis proved that the wool had been dyed with “Prussian blue,” a synthetic mineral pigment consisting of an iron cyanide salt, which had been invented in Berlin in 1704. There is no chemical relationship whatsoever between Prussian blue and the sepia of the cuttlefish.

Concerning this contradiction, Rav Herzog wrote the following remarkable hypothesis:

The Radzin tekhelet thus stands self-condemned, or the results of chemistry are to be questioned.

I would hesitate very much before condemning of fraud a man of the stamp of the late G. E. Leiner.

It would seem that the late Hasidic Chief was victimized by some fraudulent Italian chemist. On arriving in Italy Leiner, as he states himself, worked hard with a view to discovering a process for the extraction of the tekhelet dye from the Sepia off.

Attracted by Leiner’s offers of high remuneration, some clever but swindling specialist in tinctorial chemistry contrived, it would appear, to concoct Prussian dye with Sepia secretion, in such a manner as to conceal the presence of the dye…

Investigations carried out in Italy might perhaps clear up the mystery, as it is not improbable that Leiner previously to his falling into the swindler’s net had made an announcement in the Italian press offering a huge sum for the process whereby a blue of a certain nuance might be extracted from the secretion of Sepia officinalis.

(Hebrew Porphyrology, pp. 117–118)

In short, Rav Herzog wrote:

I would hesitate very much before accusing a man of Rav Leiner’s stature of fraud. I assume that he was the victim of a dishonest Italian chemist.

When Rav Leiner arrived in Italy, he worked unsuccessfully to discover a process for extracting Tekhelet from the cuttlefish. Apparently, the Rebbe offered a substantial financial reward, which attracted a specialist in chemical dyeing—a clever but dishonest man. This chemist apparently taught him how to produce Prussian blue using the cuttlefish without revealing to him the true nature of the process.

After Rav Leiner’s puzzling assertion that:

In all the scientific books dealing with the range of colors, and in all the books of those expert in chemistry, there is no information whatsoever about how to produce a Tekhelet color from the blood of any animal species,

Rav Herzog, apparently because of his knowledge of additional languages and his access to extensive scientific libraries, succeeded in reaching a positive conclusion regarding the matter. He wrote:

In 1858, the Frenchman Lacaze-Duthiers published an excellent article summarizing all the investigations and experiments that preceded him, together with a detailed report of experiments he had conducted… over a number of years.

Based upon the experiments conducted by the French scholar with the banded dye-murex, the spiny dye-murex, and the red-mouthed murex… he reached the following conclusion: the final, fundamental color is always violet.

From the time the French researcher’s article was published, the number of experiments increased.

(HaHed, Sivan 5692, p. 20)

Obviously, none of this information—the literature, findings, and evidence—was known to the Radzyner Rebbe. He therefore concluded that he had to search elsewhere, along the path described above.

What conclusion did Rav Herzog draw from these studies?

Reason tends toward the conclusion that the Tekhelet color derived from a chilazon was produced from the dyeing substance found in the banded dye-murex.

(HaHed, Elul 5692, p. 30)

He also wrote:

We have demonstrated at length that there is a strong presumption that the species known as the banded dye-murex is the chilazon of Tekhelet. On the one hand, the blue color produced from it is of a suitable quality. On the other hand, enormous piles of the remnants of its shells have been found near Tzidon, close to the place where, according to the mesorah of Chazal, the main center of the Tekhelet industry in Eretz Yisrael was situated—that is, in the portion of Zevulun near Tzidon…

(HaHed, Elul 5694, p. 17)

What, then, caused Rav Herzog to abandon this clear conclusion later on, to the point that he suggested that scientists examine the purple secretion produced by snails of the Janthina species to see whether it might be suitable for dyeing wool with Tekhelet? This theory has recently been tested and found to have no substance.

Rav Herzog wrote:

Let us consider whether the banded dye-murex, the marine snail species whose identification appears so likely, is indeed the chilazon we seek. To our disappointment, this species does not correspond at all to the sign “its body resembles the sea”… Nor does it correspond to the sign “it rises once in seventy years,” even after assuming that this expression is not literal.

(HaHed, Elul 5694, p. 18)

We see here two different attitudes toward the two elements established by the Beis HaLevi.

From the historical standpoint—which was the primary consideration for the Beis HaLevi—the banded dye-murex was certainly the proper identification of the Tekhelet chilazon, even according to Rav Herzog. But when Rav Herzog considered the halachic simanim, he withdrew his support because, according to the explanations he had received, those signs did not fit the banded dye-murex.

7. Revealing the Radzyn Dyeing Process

In 5729 (1969), I discovered among the manuscripts in Rav Herzog’s estate a long and detailed letter that he had received directly from Radzyn in 5673 (1913). It contained a complete description of the ingredients and the entire process used to dye the Radzyner “Tekhelet.”

The central chemical reaction was described in the letter as follows:

This blood [sepia—Y.Z.] is placed in a very thick vat, and ground iron is added… together with a substance as white as snow called Potasz. It is then left within a large and powerful fire for four or five hours, until the fire burns outside and inside like the fire of Gehinnom. The blood, ground iron, and white substance then melt and become one…

The reaction described here is precisely the process known since 1704, when the first synthetic dye, called “Prussian blue,” was invented. Prussian blue is an iron cyanide salt.

The synthesis may be expressed as follows:

(N), a source of nitrogen + KOH (potash) + 2Fe (iron), heated to approximately 900° → KCN (potassium cyanide) + Fe²⁺ and Fe³⁺ iron salts

6KCN + Fe²⁺, with heating → K₄Fe(CN)₆ + 2K⁺

3K₄Fe(CN)₆ + 4Fe³⁺, with acid → Fe₄[Fe(CN)₆]₃ (Prussian blue) + 12K⁺

It follows that there are no secrets involved. All the details of the process were revealed in the letter that arrived from Radzyn.

Originally, in 1704, ox blood was used as the source of nitrogen in producing Prussian blue. Later, meat or any other animal substance was used. By 1749, Prussian blue was already being used in France to dye wool and silk. During the nineteenth century, chemists learned how to prepare the pigment directly from cyanide, without using any natural material.

The “chiddush” utilized by Rav Leiner was therefore simply to use sepia as the source of nitrogen in a known chemical reaction and process—nothing more.

The chemical reaction is actually familiar to anyone who studied chemistry in school, since it is the simple analytical test used to detect the presence of nitrogen in a chemical compound.

Another interesting conclusion may be drawn from this process. On Erev Pesach, a person burns his chametz so that nothing remains except ashes. In the Radzyn process, the sepia is heated until even the metal iron melts. It is estimated that the temperature reaches approximately 900 degrees Celsius.

Therefore, even if it were possible to believe that the common cuttlefish was the authentic Tekhelet chilazon, nothing of it remains after this process. It has been completely burned away, and no chemical residue remains that can be attributed to the cuttlefish.

8. Identifying Blue in the Banded Dye-Murex

In 5731 (1971), Dr. Herbert Fouquet and Professor Hans-Joachim Bielig of Saarbrücken, Germany, published their comprehensive and penetrating study of the biochemistry involved in producing Tekhelet and argaman colors from sea snails.

They conclusively proved that only in the banded dye-murex does a blue pigment—indigotin—form spontaneously in nature alongside the strong purple color. This blue component is characteristic of this species and distinguishes it from the other dye-producing snails, which produce only purple.

This conclusion provided full scientific confirmation of an observation first reported by Professor Bartolomeo Bizio in Venice in 1833. It was later reported by Félix Lacaze-Duthiers in 1859; Professor Paul Friedländer in 1903; Professor Raphaël Dubois in 1909; Pfister in 1937; Simone Bouchilloux and Jean Roche in 1954; and, more recently, Professor Otto Elsner in Israel in 1985, André Verhecken in 1987, and Michel and McGovern in 1992.

This discovery decisively tipped the balance of the scientific evidence. I was able to state for the first time that the proper source for producing Tekhelet is indeed the banded dye-murex, which Rav Herzog had identified before subsequently withdrawing his conclusion.

Until then, all my extensive involvement in the subject—my discoveries, collection of material, and research—had remained entirely theoretical. However, once I saw that a logical conclusion could be drawn from all the available information, I asked myself whether this banded dye-murex still existed in the waters of Eretz Yisrael.

In 5741 (1981), I contacted Dr. Ehud Spanier of Haifa University after learning that he was conducting ecological research on this creature. Only then did I discover, to my great joy, that the Tekhelet chilazon was alive and well in our waters. It had not disappeared from the world.

Soon afterward, Dr. Spanier supplied living snails to my laboratory at the Israel Fiber Institute in Jerusalem. There, for the first time, I extracted from the banded dye-murex the secretion that is black like ink, and it produced the color of Tekhelet.

9. Answering Rav Herzog’s Objections: The Simanim of the Chilazon

During my research into the behavior of the chilazon in its natural environment, I was able to propose solutions to the major difficulties concerning the halachic simanim used to identify the chilazon, particularly Rav Herzog’s objections regarding the signs “its body resembles the sea” and “it rises once in seventy years.”

The source for identifying the chilazon by its signs is the Gemara:

The Rabbis taught: This chilazon—its body resembles the sea, its form resembles a fish, it rises once in seventy years, and with its blood one dyes Tekhelet. Therefore, its value is high.

(Menachos 44a)

It is commonly assumed that the sign “it rises once in seventy years” was not brought down as halachah by the Rambam when he paraphrased this beraisa:

The chilazon is a fish whose appearance resembles the appearance of the sea. Its blood is black like ink, and it is found in the Yam HaMelach.

(Hilchos Tzitzis 2:2)

It is also commonly assumed that the Rambam’s two signs, “its blood is black like ink” and “it is found in the Yam HaMelach,” have no source in Chazal and were added by the Rambam based upon his own knowledge.

Both of these explanations are difficult to accept. As we will see, neither is necessary.

A comparison of the language of the beraisa with that of the Rambam reveals three key words shared by both sources: fish, sea, and blood. This allows us to identify the corresponding signs.

A. “It Is a Fish”

The Rambam’s statement that “it is a fish” is derived from the Gemara’s statement that “its form resembles a fish.”

B. “Its Appearance Resembles the Appearance of the Sea”

The Rambam writes:

Its appearance resembles the appearance of the sea.

There is also an alternate reading:

Its appearance resembles the appearance of Tekhelet.

Its source in the Gemara is:

Its body resembles the sea.

The word ayin here means appearance or color.

When we remove a banded dye-murex from the sea, its shell is covered with a range of strong colors—purple, green, blue, brown, and others. This results from a covering of tiny, colorful organisms attached to the entire surface of the shell, a phenomenon known as biological fouling.

The floor of the sea, including the rocks and stones among which the snails live and move, is also covered with this same colorful biological growth. It is therefore extremely difficult for divers gathering the snails to distinguish between the shells and the surrounding rocks.

This phenomenon explains the siman. The word “sea” apparently does not refer to the water itself, which has no inherent color, nor to the surface of the sea, whose color changes together with the color of the sky. Rather, it refers to the colorful seabed where the chilazon is found.

C. “Its Blood Is Black Like Ink”

The Rambam’s statement:

Its blood is black like ink,

is derived from the Gemara’s statement:

With its blood one dyes Tekhelet.

In order to dye wool, a concentrated dye solution is used, and this solution is dark and black like ink.

When the “blood” is first squeezed from the living chilazon, it is still clear. It becomes dark only after the spontaneous development of the Tekhelet dye, as described by the Gemara:

As long as it remains alive, it is preferable for him, so that its dye will remain clear.

(Shabbos 75a)

Rav Herzog likewise concluded:

The intent is not the color of the blood at the beginning, but the final, fully developed color that emerges from a cloudy whitish substance through the action of light and sunlight.

(HaHed, ibid., p. 19)

D. “It Is Found in the Yam HaMelach”

After matching the three signs listed above, the remaining sign in the Rambam is:

It is found in the Yam HaMelach,

meaning the Mediterranean Sea, as that term is generally used by the Rambam.

Its corresponding source in the Gemara is:

It rises once in seventy years.

The meaning is that if the chilazon “rises once in seventy years,” then during the other sixty-nine years, so to speak, it is found in the sea, from which it must be gathered in order to produce Tekhelet.

The Rambam’s explanation, “it is found in the Yam HaMelach,” is reflected in an account brought by Rav Sander Friedenberg in his sefer Oholiav ben Achisamach. He relates what he heard from Chinese Jewish prisoners captured during the Russo-Chinese War:

I asked them about the chilazon that rises once in seventy years. He told me: When the fish reaches the age of seventy years, it rises by itself. If it is caught, however, it no longer contains the ink.

The question remains: From where did the Rambam derive his explanation that “it is found in the Yam HaMelach”?

It may be suggested that he learned it from descriptions written by classical authors. Aristotle, for example, writes that the dye-producing snails are found in the sea. If they approach the coast near the mouth of a river, they die within one day from exposure to fresh water (History of Animals, book 8, section 20).

The Roman author Pliny the Elder condemns the dyeing of clothing as an expression of luxury and moral corruption because the dye-producing snails were obtained by fishermen and divers who risked their lives in the stormy sea and its depths (Natural History, book 9, section 53).

Regarding the period mentioned by the Gemara, “it rises once in seventy years,” Rav Herzog asks:

We have no remaining record of this periodic appearance that would enable us to calculate its time… It is merely an exaggeration of the type commonly found in the words of Chazal and is not meant literally.

(HaHed, ibid., p. 18)

The expression therefore denotes extreme rarity—something exceedingly rare or virtually without limit. It may be compared to the Mishnah’s statement:

A Sanhedrin that executes one person in seven years is called destructive. Rabbi Elazar ben Azaryah says: one person in seventy years.

(Makkos 1:10)

The Gemara also states:

Those who hunt the chilazon tie and untie.

Rashi explains that this refers to the fishermen’s nets (Shabbos 74b). It therefore appears that the chilazon used for dyeing was specifically gathered from within the sea. Nets and ropes would not be needed to collect the snails if they came out of the sea and onto the shore by themselves.

The high price of the chilazon, mentioned at the conclusion of the beraisa—“therefore, its value is high”—apparently relates to the immediately preceding sign, “with its blood one dyes Tekhelet.”

In other words, the other snails are not expensive because their blood is not used to dye Tekhelet. This implies that Tekhelet is produced specifically from one particular and unique chilazon.

This explanation fits very well with the conclusion of scientific research regarding the banded dye-murex, as explained above.

10. “The Hidden Treasures of the Sand”

According to Chazal, the chilazon fishermen operated from the “Ladders of Tyre”—Rosh HaNikrah—until Haifa (Shabbos 26a), within the territory of the tribe of Zevulun (Megillah 6a).

Along this rocky coastline, archaeologists have discovered the remains of installations used for dyeing with sea snails. Beside them were large piles of broken banded dye-murex shells that had been used for dyeing in ancient times.

In the sea along these same shores, the identical banded dye-murex still lives today in large numbers. Its habitat consists of rocky areas or coarse sand covered with stones, at depths ranging from approximately 1.5 to 12 meters.

It can produce the same dyeing substance that has been chemically identified in archaeological remains dating back thousands of years.

In Moshe Rabbeinu’s brachah to the tribe of Zevulun, “and the hidden treasures of the sand,” the word “hidden” refers to the Tekhelet chilazon, as Targum Yonasan says on Devarim 33:19:

They will catch the chilazon and dye from its blood the Tekhelet threads for their garments.

Regarding the mesorah that the Tekhelet chilazon hides itself in the sand, we should mention Dr. Spanier’s observation in the Bay of Akko in 5740 (1980). During the summer months, the banded dye-murex snails bury themselves in the sand and cannot be found on the surface of the seabed except during the winter.

In this connection, Verhecken observed during the summer of 5745 (1985) that the snails are indeed buried in the sand during the day, but emerge at night to hunt for food.

11. Renewing the Mitzvah of Tekhelet in Practice

Once Rav Eliyahu Tavger shlita of the Ramot neighborhood in Jerusalem became convinced that the banded dye-murex had been correctly identified as the Tekhelet chilazon, he decided to restore Tekhelet to his own tzitzis.

After consulting with Professor Otto Elsner of Shenkar College in Ramat Gan in order to learn the technical process of dyeing with the chilazon, he personally gathered the snails from the sea, dyed the Tekhelet lishmah, and placed a thread of Tekhelet in his own tallis and in the talleisim of hundreds of others.

Because the chilazon is a protected species, Israeli law prohibits capturing it without a special and limited permit from the Nature Reserves Authority. It is therefore impossible to obtain enough snails from the sea to produce Tekhelet on an industrial scale.

Importing the raw material from neighboring countries, where the snails are sold as food, provides only a partial solution. It is doubtful whether the necessary official import and export permits can be obtained on a permanent basis and on a mass scale.

To establish a Tekhelet dyeing operation, a steady long-term supply of snails must be secured in advance.

There is always a danger, chas v’shalom, that the chilazon could become extinct in its natural habitat because of industrial pollution in the coastal waters or some other natural disaster.

For the long term, arrangements must be made to preserve the chilazon in a protected habitat, both for tzitzis and for the Bigdei Kehunah that will be needed for the Beis HaMikdash, may it be rebuilt speedily in our days.

Footnotes

• The author is chairman of the Association of Research Workers in Israel and a senior scientist, now retired, at the Israel Fiber Institute of the Ministry of Industry and Commerce. He serves as the scientific director of the Keren HaTekhelet organization.
• During the most recent Elul, Rav Tzvi Hershel Schachter shlita visited Yeshivat Sha’alvim, and I saw that he was indeed wearing Tekhelet in his tallis. He explained to me that, in his view, all of Rav Yosef Dov Soloveitchik’s arguments against renewing Tekhelet had already been answered by those restoring Tekhelet in our generation, and that there is virtually no doubt that the chilazon is the above-mentioned murex. He also said that there is a conclusive proof that archaeological evidence may be used in halachic matters: the Gemara in Bava Basra 74a entertained the possibility of determining the halachah of tzitzis from the garments of the deceased generation of the Midbar. (Editor’s note by Yoel Katan.)