Identifying the Murex trunculus as the Original Tekhelet

Rabbi Yaakov Epstein

Introduction[1]

The commonly accepted view today among most of those dealing with the subject is that the Tekhelet of tzitzis was produced from the snails known as murex. In this article we will try to examine how far this identification can be relied upon in order to fulfill the mitzvah with certainty. In order to establish the identification of Tekhelet, we first have to find a clear and definite connection between the murex snails known to us today and the chilazon of Tekhelet used for tzitzis, based on what is known from our own sources.

A. Tekhelet Is Kosher Only If It Comes From the Chilazon

The Tosefta [Menachos 9:6] states:

“Tekhelet is kosher only from the chilazon; if it is not from the chilazon, it is pasul.”

The Beraisa de-Tzitzis likewise says:

“Tekhelet may only be dyed with the chilazon.”

The Rambam writes at the beginning of Hilchos Tzitzis:

“One takes a woolen thread dyed like the appearance of the sky and winds it around the other threads, and this thread is what is called Tekhelet.”

Later [Tzitzis 2:2], he describes the dyeing process:

“Afterwards they bring the blood of the chilazon, which is a fish whose appearance resembles the sea, and its blood is black like ink…”

He similarly writes in his Peirush HaMishnayos [Menachos 4:1]:

“This thread is called Tekhelet, as the Torah says, ‘And they shall place upon the tzitzis of the corner a thread of Tekhelet.’ We do not have it today because we do not know how to dye it, since not every bluish shade in wool is called Tekhelet. Rather, it is a specific Tekhelet which is not possible today…”

And in Hilchos Klei HaMikdash [8:13], the Rambam writes:

“The Tekhelet mentioned everywhere is wool dyed like the essence of the heavens, mixed from kochal.”

The Mishneh LaMelech comments:

“He wrote something similar at the beginning of Hilchos Tzitzis, and I do not know why Rabbeinu did not explain that this color must come from the blood of the chilazon. Even if another dye were found whose appearance resembled the heavens, it is obvious that it would not work, since it is not from the blood of the chilazon. At the beginning of chapter 2 of Hilchos Tzitzis, Rabbeinu explained that the Tekhelet mentioned regarding tzitzis comes from the blood of the chilazon, and it is obvious that the same applies here. Perhaps he relied on what he already wrote in Hilchos Tzitzis.”

Some later authorities wanted to infer from the Rambam’s silence regarding the chilazon in Hilchos Klei HaMikdash that the Tekhelet used in the Beis HaMikdash does not necessarily have to come specifically from the chilazon. See Ir HaKodesh VeHaMikdash [vol. 5, pp. 43–46], where this is discussed and the opposing opinions are cited. Regarding tzitzis, however, it appears that everyone agrees that Tekhelet is kosher only if it comes from the chilazon.

B. The Identification of Ancient Argaman and Royal Tekhelet by Researchers

Non-Jewish sources, including ancient historians and researchers such as Pliny and Aristotle, contain descriptions of the chilazon used to produce argaman and royal Tekhelet — meaning the dyes used for royal clothing, as distinct from the Tekhelet of tzitzis — as well as descriptions of the creature’s way of life and how the dye was extracted.

These accounts describe the chilazon from which purpura, the argaman dye, was produced, as well as the chilazon used for hyacinth, a bluish-purple form of purple dye. [These sources are brought in Rabbi M. Burstein’s book HaTekhelet.]

Likewise, at archaeological sites near ancient dyeing installations, enormous quantities of broken murex shells have been found, broken specifically opposite the dye gland. This is evidence that these shells were used in ancient times to produce dyes.

Only four pieces of blue-dyed cloth have been discovered anywhere in the world whose dye has been identified as coming from murex. None of them, however, is connected to tzitzis. Other ancient textiles dyed a Tekhelet-like color were found to have been dyed with plant-based substitutes [kala ilan].

C. The Tekhelet of Tzitzis Comes From the Argaman Chilazon

General Background

The accepted opinion among those working on identifying Tekhelet in the present generation is that the chilazon of Tekhelet used for tzitzis was the same type of chilazon from which argaman and royal Tekhelet were produced in the ancient world.

[The two alternative suggestions — the common cuttlefish, identified by the Radzyner Rebbe as the chilazon, and the Janthina snail, proposed by Rabbi Herzog — have been completely rejected by those currently involved in the subject. This is not the place for a full discussion.]

Along the coast of Eretz Yisrael there are three species of snails from which these dyes were produced, all belonging to the same family: the blunt-spined murex, the sharp-spined murex, and the red-mouthed rock shell. (I also saw another sea snail on display called the “shiny murex,” but I have not found anyone discussing it, and this requires clarification.)

These snails possess a dye gland. While the dye substance is inside the snail it is transparent, but after being removed it becomes a dyeing substance which, through chemical processes, can produce colors ranging from blackish-purple, through reddish-purple, all the way to turquoise-blue.

Those working on the identification of Tekhelet today rely not only on Chazal and the Rishonim, but also on research into historical and archaeological sources, marine biology, and linguistics.

Among the sources in Chazal, special attention should be given to the version of the Yerushalmi at the beginning of Berachos quoted by the Raavyah, where Tekhelet is referred to as porphyrin. From this one could understand that the source from which the dye for the mitzvah of tzitzis was produced was the same source used for ordinary purpura — argaman.

Rabbi Binyamin Mussafia, author of the Mussaf HaAruch and a descendant of the Spanish exiles, writes similarly, as does the Chavos Yair in his Mekor Chaim, although they do not bring proofs for the identification.

We do not possess even a single actual Tekhelet thread from the time when Tekhelet was still practiced among Klal Yisrael. No tallis with its tzitzis has survived from that period. Therefore we cannot rely on chemical analysis of an actual Tekhelet thread in order to determine its components and thereby identify its source.

The royal Tekhelet threads that were found cannot serve as absolute proof regarding the source of the Tekhelet of tzitzis. At the end of the day, how do we know with certainty that both came from the same source?

Thus, even scientific investigation across various fields, with one field checked against another, remains scientific research containing elements of uncertainty. Direct testimony and a mesorah, if available, would unquestionably be preferable.

Likewise, the ancient argaman dyeing sites do not clearly prove anything about the production of Tekhelet. No Tekhelet threads were found there, only shells broken opposite the dye gland and, in some places, remnants of dye tending toward argaman.

Other than the sources mentioned above, neither our own sources nor outside sources explicitly identify the particular chilazon from which Tekhelet for tzitzis was produced. Every later identification therefore depends on drawing conclusions from known evidence and applying them to the Tekhelet of tzitzis.

Some rabbanim who investigated the issue relied more heavily on the simanim of the chilazon gathered from Shas and the Rishonim, as did the Radzyner Rebbe and Rabbi Herzog. Others used a process of elimination, rejecting all possible animals that did not fit until arriving at the murex, as Rabbi Tavger did in his article on Tekhelet at the end of his sefer Kelil Tekhelet.

According to all of these approaches, we still have to determine whether the mitzvah of a thread of Tekhelet can actually be fulfilled today, or whether Tekhelet is still considered hidden from us. We must also determine whether other questions that have been raised, such as the precise shade, have really been resolved.

1. The Methods and Proofs of the Modern Identifiers

The Radzyner Rebbe reached his identification based upon various simanim, and other researchers followed a similar approach, including Rabbi Herzog zt”l and, yibadel lechaim, Dr. Ziderman.

The simanim themselves require explanation, and the comparison between those simanim and the proposed animal is uncertain.

In addition, the signs do not all come from one source. Some are taken from the description of the chilazon in the Bavli. Others come from the Yerushalmi in Shabbos, whose interpretation is disputed between the Radzyner Rebbe and the Korban HaEidah. Others are taken from comparisons to Mishnayos in Bechoros and Keilim, where the word chilazon is used to describe, in one case, a certain eye deformity and, in another, a certain piece of a lock. Still others are based on the Rambam, early Kabbalistic works such as Sefer HaKanah, and aggadic statements in the Gemara and Midrash.

The very need to gather so many different simanim is itself difficult to understand, especially since each individual siman can be interpreted in different ways.

It therefore appears to me that the identification remains a safek.

Apparently for this reason, most of the Gedolei Yisrael, both in the past and today, did not accept the Radzyner Rebbe’s identification as certain, or even necessarily as a halachic safek that one must take into consideration.

The Aruch HaShulchan [Orach Chaim 9:12] writes very sharply:

“Know that a few years ago, one person boasted that he had found the chilazon and produced Tekhelet from it, and some people followed him. But the Gedolei HaDor and Klal Yisrael did not listen to him, and the matter fell away, until the righteous redeemer comes, speedily in our days.”

The Yeshuos Malko [Orach Chaim 1–2] likewise writes that this identification is not certain.

It is also reported in the name of the Chafetz Chaim [quoted in HaTekhelet, p. 189, based on R. M. M. Yoshor’s The Chafetz Chaim: His Life and Work]:

“I would not put my head into the fire and risk performing the avodah of the Beis HaMikdash based on his theory” — meaning the theory of the Radzyner Rebbe.

Rabbi Menachem Mendel Kasher similarly wrote in Torah Sheleimah [supplements to vol. 23] that the uncertainty regarding the Radzyner identification is too great.

Perhaps the strongest proof of all that the Radzyner Rebbe’s identification was not accepted even as a halachic safek is that both Rabbi Herzog, who leaned toward identifying the Janthina as Tekhelet, and today’s rabbanim and researchers who accept the murex identification, did not consider the cuttlefish’s simanim compelling.

Likewise, the other rabbanim and researchers who relied on simanim collected from the above sources were not spared the same specific and fundamental difficulties raised against the Radzyner Rebbe’s approach.

The Process of Elimination

Rabbi E. Tavger, in his article on Tekhelet at the end of Kelil Tekhelet, uses a process of elimination: he considers all reasonable possibilities and rejects them one by one until only one remaining answer is left which cannot be rejected.

Anyone using such a method must first determine whether the primary criterion used to eliminate the other possibilities is actually correct, and whether the elimination of the alternatives was truly justified.

Rabbi Tavger lists the following criteria for identifying the original chilazon of Tekhelet:

1. The chilazon is an animal.
2. It is found in the sea — specifically the Mediterranean.
3. It is not a mountain snail.
4. The chilazon has a protective casing or shell.

The first two criteria are agreed upon.

The third criterion, however, contradicts Rashi’s approach, which appears in three places — Megillah 6a, Sanhedrin 91a, and Menachos 44b — that the chilazon emerges from the sea and comes onto land or into the mountains. We do not find such behavior among the murex snails.

The fourth criterion, that the chilazon has a shell or casing, is also not so simple. The Radzyner Rebbe interpreted the “casing,” as well as the bones and sinews mentioned in the Yerushalmi in Shabbos, differently from Rabbi Tavger.

Rabbi Tavger also cites the Raavad’s commentary to Sefer Yetzirah, which says:

“It is impossible to determine whether the chilazon belongs among fish or among plants, because it is alive and moves, yet it does not change its location, because it is embedded and fixed in the ground.”

But this description does not fit an ordinary land snail either. Anyone who watches them can see that they are not fixed in place. They cling to surfaces and move, leaving behind a trail of slime.

Rabbi Tavger also cites the Aruch, which says that its form is like a ring, as well as drawings that accompanied various manuscripts. But neither the description “ring” nor the drawings really resemble a snail.

After establishing his criteria and supporting them from various sources, Rabbi Tavger examined all suitable snails capable of producing dye and arrived at the murex.

This rests on two assumptions:

1. We know all species of snails found in the Mediterranean.
2. No species that existed in the past have since disappeared.

To establish these two assumptions, he relies upon the scientific consensus.

For the second assumption, he argues that there have been no major changes in natural conditions since the time of Chazal, nor was there deliberate human extermination of snails and similar creatures. Therefore, there would be no reason for the chilazon to have disappeared.

For the first assumption, he argues that scientists have been searching for previously unknown snail species for many years, and genuine new discoveries in this field are extremely rare.

It is very difficult to prove these assumptions, particularly the assumption that natural conditions have not significantly changed over the last two thousand years…[2]

We should add that Rabbi Herzog was fully aware of the researchers’ inclination to identify the murex as the chilazon of Tekhelet. Nevertheless, he rejected their approach because one Midrash did not fit the murex according to his understanding — even though he certainly knew that there are always other possible interpretations — and because the color they produced from the murex did not match the Tekhelet described by Chazal, even though he understood chemistry and knew that changing shades is not necessarily very significant.

It appears that the reason he was unwilling to accept the researchers’ identification was that he did not view their identification of the chilazon of Tekhelet as conclusive.

2. Examining the Gemara and Midrashim

Unfortunately, with one exception that will be discussed below, our sources do not identify the animal from which the dye was produced by any specific name other than the generic term chilazon.

Therefore, all proposed identifications are based entirely upon simanim derived from the Gemara and Midrashim.

The only source that gives something more specific is the Raavyah, who quotes a passage from the Yerushalmi in Berachos that was apparently present in the version before him:

“And the Yerushalmi has the text: between Tekhelet and karti, between pirpiron and peripinin. It is a cloak which in the vernacular is called pirpura, and there is another which resembles it somewhat.”

Pirpura is the name of the chilazon which, according to the testimony of Greek and Roman historians, was used to produce both argaman and Tekhelet for royal garments.

Accordingly, it would seem that we have a direct source identifying the chilazon of Tekhelet.

However, this source itself requires examination.

First, we have no other source for this version of the Yerushalmi. I have not found even one other Rishon or Gaon who quotes the Yerushalmi this way. This raises the possibility that the sentence was a later addition which entered the manuscript of the Yerushalmi that stood before the Raavyah.

That being said, there are other examples of unique readings in the Yerushalmi that survive only in quotations by Rishonim and are absent from our editions.

In addition, the term porphyra appears dozens of times in Chazal — in both Talmudim, in Midrashim, and even in the Zohar — but nowhere is it identified directly or indirectly with tzitzis.

If the Tekhelet of tzitzis came from the same source as porphyra, why are Chazal completely silent about this and never hint to it?

One can answer that Chazal did not refer to Tekhelet itself by the name porphyra, and therefore saw no reason to identify its source as porphyra. But if so, why would the Yerushalmi itself have said this?

Likewise, Tekhelet is mentioned many times by Chazal, yet in no source from the period of Chazal is Tekhelet identified as porphyra. This could be either because Tekhelet was never called by that name or because it did not come from the same chilazon.

This makes it very difficult to identify Tekhelet with absolute certainty as a dye produced from the murex.

Bottom line: despite the Raavyah, we have not escaped the safek.

From the way Chazal distinguish between porphyra and Tekhelet, it appears to me that Chazal called an argaman garment porphyra, whereas a garment of Tekhelet was not called that. If so, there may have been no connection between porphyra and Tekhelet at all.

However, Pirkei DeRabbi Eliezer [ch. 49] says:

“Rabbi Pinchas says: Mordechai became king, as it says, ‘And Mordechai went out from before the king in royal clothing of Tekhelet and white…’ Just as a king wears porphyra, so did Mordechai, as it says, ‘And Mordechai went out from before the king in royal clothing of Tekhelet and white…’”

At first glance, this appears to prove that Tekhelet is porphyra.

However, the proof can be rejected. First, porphyra here refers to the royal garment as a whole, not specifically to the Tekhelet. Furthermore, even if porphyra is a name for Tekhelet, the discussion is not about tzitzis. How do we know that Tekhelet for tzitzis and the blue dye used for royal clothing came from the same source?

Shabbos 26a states:

“‘And from the poor of the land Nevuzaradan, chief executioner, left behind as vine-dressers and yogvim’… ‘Yogvim’ means those who hunt the chilazon from the ladders of Tyre until Haifa.”

Rashi explains:

“Velyogvim — from the language of winepresses, because they squeeze and break open the chilazon in order to extract its blood, as we say later in the chapter Klal Gadol. Nevuzaradan left them there for the clothing of the king.”

We learn from Rashi that the material used for Tekhelet was the same material used to dye royal clothing, and that it came from the chilazon.

But this Midrash still does not identify which chilazon it was, and therefore does not advance the identification itself.

It is true that about four blue threads from ancient times were found — at Palmyra, Ein Bokek, and Cyprus — which researchers claim were dyed from the chilazon. But they clearly are not tzitzis threads, and therefore it is difficult to decide the halachic issue of the mitzvah of tzitzis based on these findings.

In my opinion, the very ability to identify these threads as having been dyed from the chilazon also requires further clarification.

According to those who maintain that Tekhelet was produced from the murex and that its color was blue, this means chemically that the indigo had been isolated completely, with the bromo-indigo and dibromo-indigo removed.

But if so, it should no longer be possible to distinguish the source of the dye — whether it came from a plant, namely kala ilan, or from an animal, namely the chilazon.

If so, what proof is there that the dyeing substance came from murex?

Furthermore, I have not found any source in Chazal stating that argaman and Tekhelet came from the same source, as those producing Tekhelet from murex maintain. Nor did the earlier authorities mention such a connection even by way of a hint.

See Midrash Tanchuma [Terumah 5]:

“HaKadosh Baruch Hu said to them: You are not bringing from your own possessions, but rather from the spoils of the sea… ‘Tekhelet and argaman’ — Tekhelet, which is dyed with blood, as a remembrance of the sign which the forefathers of the world already established; tolaas, as it says…”

Anyone examining the Midrash will notice that the explanation of argaman seems to be missing, and the Midrash jumps from Tekhelet directly to tolaas.

One could argue that the explanation of argaman fell out of the text and that the correct reading should be:

“Tekhelet and argaman, which are dyed with blood…”

However, I found no support for this reading, nor does such a version appear in other manuscripts of Midrash Tanchuma.

There is an additional difficulty: argaman appears dozens of times in Chazal, and just like porphyra, nowhere is it stated that its source is a chilazon — certainly not that it comes from the very same chilazon used to produce Tekhelet.

Argaman itself is counted among the praises of Eretz Yisrael [Bereishis Rabbah 91, on “Take from the choice products of the land”].

By contrast, it is stated many times that Tekhelet is produced from the chilazon.

Therefore, the connection between Tekhelet and argaman — that both come from the same source — still requires proof, in my opinion.

3. Examining the Rishonim and Acharonim

The Raavyah

The clearest source for identifying the murex as the source of Tekhelet for tzitzis is the Raavyah. He had a version of the Yerushalmi from which it seems explicit that Tekhelet is porphyra. His words were discussed above.

Rav Nachshon Gaon

Before the Raavyah, Rav Nachshon Gaon also discussed Tekhelet in a responsum quoted in the Ittur [Hilchos Tzitzis]:

“In a question to Rav Nachshon, Rosh Mesivta: Tekhelet resembles the sea, and the sea resembles the sky, and the sky resembles the Kisei HaKavod. Its name in Arabic is lamasma, and argaman is banafsaja.”

The Arabic term lamasma used here is unfamiliar.

In Pesil Tekhelet [by the Radzyner Rebbe, p. 64], he cites the great Canon [Book II, section 269], the medical work of Ibn Sina, which speaks of a chilazon whose hard outer shell is taken for medicinal use, and whose name in ancient Latin is lamasia.

The Rebbe explained that this word was borrowed from Arabic and referred to the common cuttlefish, which in his opinion was the chilazon of Tekhelet.

He repeated this in Ein HaTekhelet [section 24, p. 124], where he rejected the suggestion that the Arabic word was simply a general term for sea creatures and not the name of the chilazon specifically. If that were so, he argued, there would be no reason for Rav Nachshon to tell us that this was the Arabic name of Tekhelet.

However, it requires explanation why Rav Nachshon connects the Gemara’s statement “Tekhelet resembles the sea…” with argaman, and what forced him to do so. Since we do not have the full wording of the responsum, it is difficult to know whether perhaps the question dealt with the materials of the Mishkan or something similar, in which case the connection would be understandable.

Rabbi Tavger cites a version of the Ittur according to which Tekhelet is the color lon asma, meaning “the color of the heavens.”

According to this version, it is easier to understand why Tekhelet and argaman are mentioned together, since the responsum was simply listing colors.

The difficulty, however, is Rabbi Tavger’s wording. The version appearing in the Radzyner Rebbe’s sefarim is the same as that found in our editions of the Ittur: lamasma, not lon asma.

One could suggest that Rav Nachshon Gaon’s words were truncated, and that the intended meaning was something like: “And its name… whose Arabic translation is al-masma,” with the initial alef dropped or omitted by copyists who did not understand Arabic.

But even according to this possibility, the actual name of the chilazon would have fallen out of the Ittur, and the possibilities remain open.

I asked experts in Arabic about the meaning of the two Arabic terms in Rav Nachshon Gaon’s responsum: whether they refer to a particular animal, to a color, or perhaps to both.

Rabbi Kapach replied:

“These two words refer only to appearances and shades. The first is like the appearance of the blue dome covering the earth, and the second, which translates argaman, is the purple shade named after the plant called banafsaj, which is commonly used as a remedy for coughs.”

Rabbi Nissim Sabato discussed the matter with Professor Blau. Neither of them knew the meaning of lamasma. Regarding argaman, however, they agreed with Rabbi Kapach and noted that today the word argaman is used for a red color, whereas according to Rav Nachshon Gaon it was blue tending toward violet.

The conclusion from all this is that Rav Nachshon Gaon does not provide a clear identification of the chilazon of Tekhelet. At most, according to some readings and translations, he identifies the color of Tekhelet.

The Rambam

In Hilchos Tzitzis the Rambam describes the chilazon from which Tekhelet is dyed:

“It is a fish whose appearance resembles the sea, whose blood is black like ink, and it is found in the salty seas” — meaning salt water rather than fresh water.

This description could possibly be understood as referring to murex snails while they are in the sea, but the expression “its blood is black like ink” does not fit the dye liquid of the murex.

One could answer with some difficulty that the Rambam knew the dyeing substance in the form of a dried powder rather than in its state immediately after the snail was broken open, but the explanation remains forced.

See also Rabbi Kapach’s commentary to Hilchos Tzitzis [2:2, note 6], where he understands the Rambam literally as describing a type of fish and does not accept any of the identifications — neither that of the Radzyner Rebbe, nor Rabbi Herzog’s, nor the murex identification commonly accepted today.

Rashi

Rashi’s commentary to Sanhedrin [91a] does not fit any of the commonly accepted identifications.

He writes:

“A worm which emerges from the sea once every seventy years, and they dye Tekhelet with its blood; initially only one chilazon can be seen on the entire mountain…”

The Gra, in his glosses to the Sifrei [Vezos HaBerachah 354], even deletes the word “in the sea” which appears in the Sifrei.

As noted earlier in the section on scientific research, Rashi’s description of the chilazon as an animal that comes up from the sea onto dry land does not fit the murex.

Additional Early Poskim

The Radbaz [Responsa, vol. 2, siman 685] writes:

“In the portion of Zevulun it would come up by itself from the sea onto dry land, and they would gather it. After Yisrael went into exile, it no longer came up… Yet Chazal said ‘hunters of the chilazon,’ implying that they had to hunt it.”

Neither phenomenon fits the murex: neither its coming up from the sea onto land nor its supposedly changing its behavior after the Churban, so that it no longer comes up on land and instead must be caught with nets.

(It appears from his words that the Radbaz himself did not have practical familiarity with Tekhelet.)

The Binyamin Ze’ev [siman 195] writes:

“It is a fish whose appearance resembles the sea, whose blood is black like ink, and it comes up once every seventy years, as Rashi explains in Shabbos, chapter Klal Gadol…”

He combines Rashi’s description with that of the Rambam, and his description therefore fits the murex very poorly, as explained above.

(It also appears from his words that he did not personally know the chilazon.)

D. The Color of Tekhelet

1. Examining the Rishonim and Acharonim

The Rambam’s Definition of the Color

The Rambam writes in Hilchos Tzitzis [2:1]:

“The Tekhelet mentioned in the Torah everywhere is wool dyed like that which is mixed into kochal, and this is the appearance of the sky visible to the eye when the sky is clear… Anything not dyed with that particular dyeing is pasul for tzitzis, even if it has the appearance of the sky, such as if it was dyed with istis or with other darkening substances…”

Based on these words, Rabbi Kapach [note 2] writes that according to the Rambam the color of Tekhelet is a blue tending toward black.

His proofs are based on the comparison to the color produced from istis, the statement in halachah 2 that the blood of the chilazon is black, and the Midrash [Bamidbar Rabbah 2:7]:

“Yissachar was sapphire, and his flag was colored black resembling kochal.”

Chazal also compare Tekhelet to sapphire and to the Kisei HaKavod [Menachos 43b].

In my opinion, however, these proofs are not compelling.

The word pasuch means mixed, as is clear from the Rambam’s commentary to Negaim, chapter 1. If so, the color could be what we commonly call Tekhelet today — blue mixed with white, producing a lighter blue.

The Rambam uses the word black both for literal black [Hilchos Tefillin UMezuzah 3:1, 14] and more broadly for a dark color [Hilchos Avodah Zarah 12:10; Terumos 14:1; Tzaraas 8:10; Edus 1:6].

The Rambam does not describe Tekhelet itself as a “darkening” dye. Rather, he uses that term for its imitation. Thus, more than telling us that Tekhelet is dark, he may be telling us that it is not as dark as its imitation.

See also Hilchos Shechitah [7:17, 19], where he uses “black like ink” for a forbidden appearance, but “black like blue” for a permitted one.

It also seems difficult to depart from the Rambam’s own statement that Tekhelet is the color of the sky.

Similarly, in Hilchos Yesodei HaTorah [3:3], he describes the heavens as being the color of Tekhelet.

And in Hilchos Klei HaMikdash [8:13] he writes:

“The Tekhelet mentioned everywhere is wool dyed like the essence of the heavens, mixed from kochal.”

[It should be noted that Rabbi Kapach’s own position is that Tekhelet means specifically the color of a dark sky. He writes this in his note to Rav Saadia Gaon’s translation of Shemos 25:4.

Rav Saadia translates Tekhelet as asman-gun, meaning:

“Like the color of the heavens in their clarity, which are very blue and tend toward black.”

The translation itself, however, simply means “sky color.” The claim that it specifically means a dark sky is Rabbi Kapach’s own explanation.]

As for Rabbi Kapach’s proof from the sapphire stone, nothing definite can be established from comparisons of this sort, certainly not an exact shade, especially when the comparison is to the Kisei HaKavod.

See also Ibn Ezra’s long commentary to Shemos 28:9, where he discusses the shade of the sapphire stone.

Furthermore, the very Midrash Rabbi Kapach cites as proof seems to contradict his conclusion:

“Regarding the signs: each nasi had a flag, and each flag had a color corresponding to the precious stone on Aharon’s heart… Yehudah was nofech, and the color of his flag resembled the heavens, with a lion drawn on it. Yissachar was sapphire, and his flag was black resembling blue…”

The Midrash clearly distinguishes between dark blue tending toward black and the color of the heavens.

Since the Rambam compares Tekhelet to the color of the heavens — as do Rav Saadia Gaon and Rav Nachshon Gaon — it is difficult to reinterpret their words.

(It is also very difficult to accept the claim that the color of the sky contains black. In any event, it does not matter what name one gives the color, as long as it resembles the sky.)

Reconstructing the Exact Shade

Another issue in restoring Tekhelet is determining its precise shade.

The author of Besamim Rosh writes that the reason the mitzvah of Tekhelet cannot be restored is:

“Because it is impossible to reproduce the exact appearance of a color based upon what is written in a book.”

[Regarding the authenticity of Besamim Rosh, which has been suspected of being a forgery, see Noam, vol. 2, in the article of Rabbi Y. P. Perla, as well as Rabbi M. M. Kasher’s note in the supplements to Parashas Terumah, siman 3. See also the editorial note on this subject in the previous issue, p. 45.]

2. The Modern Tekhelet Dyeing Process and Its Compatibility With the Dyeing of Chazal

The dyeing process in the time of Chazal is described in Menachos 42b:

“We bring the blood of the chilazon and various ingredients, place them into a pot, and boil them.”

The Rambam writes [Tzitzis 2:1–2]:

“The Tekhelet mentioned regarding tzitzis must be dyed with a known dyeing method which remains beautiful and does not change. Anything not dyed with that dyeing is pasul for tzitzis, even if it has the appearance of the sky…

How is Tekhelet for tzitzis dyed? The wool is taken and soaked in lime. Afterwards it is washed until it is clean, and boiled with ahala and similar substances, as dyers normally do, so that it will absorb the color.

Afterwards they bring the blood of the chilazon… place the blood into a pot, put various ingredients into it such as kamonia and similar substances, in the manner dyers normally do, boil it, and place the wool into it until it becomes like the appearance of the sky. This is the Tekhelet of tzitzis.”

From the Gemara’s vague wording and the Rambam’s repeated expression “in the manner dyers normally do,” it would seem that Tekhelet dyeing was essentially like any other dyeing process, with the specific intention of the dyeing being what was unique.

The Rambam adds one condition:

“A known dyeing which remains beautiful and does not change.”

From the Rambam’s language, it appears that we were not commanded to use one specific technical process. Rather, any dyeing process is kosher as long as the dyeing material is the blood of the chilazon and the resulting Tekhelet retains its beauty.

The Gemara in Menachos also gives tests for distinguishing genuine Tekhelet from wool dyed with kala ilan, based on the durability of the dye.

Rashi and the Rambam disagree over exactly which materials are used in those tests, based on their different interpretations of the sugya.

The dyeing process revived today was developed by Professor Otto Elsner z”l, based upon his scientific and professional knowledge together with descriptions by Greek and Roman historians of the dyeing processes used in antiquity.

Those who actually carry out the dyeing [the Ptil Tekhelet organization] tested the process using the substances mentioned by both Rashi and the Rambam and reported that the color remained unchanged.

Apparently, from this perspective there is no reason to be concerned that the dyeing is defective, even though the modern process is not identical to the process described in Shas.

However, another question should be raised regarding the validity of the modern production process for purposes of the mitzvah.

Professor Elsner himself acknowledged that his dyeing process essentially isolates the chemical dye molecules and removes all the organic material from the blood of the chilazon.

This means that in the final dyed product produced today, it is impossible to distinguish between dye derived from the blood of the chilazon and dye derived from the indigo plant — which is kala ilan — or even dye produced entirely from synthetic chemicals.

The tests mentioned in the Gemara would give the same results for all of these dyes.

It appears that this fact by itself does not invalidate the use of Tekhelet. Although the tests were used to verify the origin of the dye, the halachic validity of Tekhelet does not depend upon the ability to perform such a test. Therefore, our inability to verify its origin through the test does not itself invalidate Tekhelet which in fact came from the chilazon.

It could also be argued that today’s dyeing process destroys the substances that once allowed one to distinguish between the two sources of dye, and perhaps even destroys the substance responsible for the exceptional durability of genuine chilazon Tekhelet.[3]

On the other hand, one could argue the exact opposite: perhaps modern chilazon dyeing is not inferior to the dyeing of Chazal at all. Rather, modern kala ilan dyeing has become superior due to advances in chemistry and dyeing technology.

Accordingly, when producing Tekhelet today, there is a greater need to verify the reliability of the source material, since modern imitations cannot necessarily be detected.

Nevertheless, none of the problems raised here are sufficient to reject the use of murex Tekhelet on the grounds that the dyeing process itself is invalid.

Summary and Conclusions

The conclusion of our investigation is that it has still not been demonstrated with certainty that the various murex species are the chilazonim from which the Tekhelet dye for tzitzis was produced.

The precise shade of Tekhelet is likewise not agreed upon among the Rishonim and Acharonim, and it is not clear that the dyeing processes developed today correspond to the processes used by Chazal.

Accordingly, fulfilling the mitzvah of Tekhelet in tzitzis today is possible. However, because of the doubts raised regarding its identification, it should be viewed as a middas chassidus: those who wear it demonstrate their love for the mitzvos of Hashem.

Those who do not wear it, however, are not, chas veshalom, being mevatel a mitzvah, nor even necessarily ignoring a safek mitzvah. Rather, they maintain that because of the high level of uncertainty, the obligation has not yet taken effect.

Be’ezras Hashem, when Tekhelet is revealed and established with certainty, all of Klal Yisrael will merit to place Tekhelet on their talleisim.

Obviously, today there can be no discussion at all of permitting kilayim in tzitzis as long as the identification of Tekhelet is not certain.