Can We Identify the Techeiles?

Parshas Shelach includes the mitzvah of wearing techeiles on our tzitzis. Rashi, in the beginning of Parshas Korach, mentions that the followers of Korach donned garments that were completely techeiles. Therefore, whether we are in a place that reads Shelach this week or one that reads Korach, it is appropriate to read about:

Can We Identify the Techeiles?


When we are commanded about wearing tzitzis, the Torah includes two mitzvos. In addition to the mitzvah of wearing tzitzis threads on the corners of the garment, there is an additional mitzvah that some of the tzitzis threads should be dyed with a special dye called techeiles. (There is a dispute among the Rishonim how many of the tzitzis threads are to be dyed techeiles.) This dye must be made from a species called chilazon (Tosefta Menachos 9:6).

Although the use of techeiles stopped over a thousand years ago, there have been a few attempts within the last 140 years to reintroduce the practice of wearing techeiles threads alongside the white threads. This article will present the differing opinions on this question and some of the issues that have been raised.

At the time of the Gemara, the nature of chilazon and its manufacture was still known and practiced (see Menachos 42b). However, some time after the period of the Gemara, the use of techeiles ended. By all indications, techeiles fell into disuse sometime between the end of the period of the Rabbonim Sabora’im, who completed the editing of the Gemara around the year 4330 (570), and the time of Rav Ahai Gaon, the author of the She’iltos, around 4520 (760).

It is unclear why the Jewish people stopped using techeiles. Numerous theories have been suggested why wearing techeiles ended. The wording used by the midrashim is “now we have only white tzitzis, since the techeiles was concealed” (Medrash Tanchuma, Shelach 15; Medrash Rabbah, Shelach 17:5). Some poskim understand that there are halachic or kabbalistic reasons why techeiles should not be worn until moshiach comes (Shu”t Yeshuos Malko #1-3). According to this opinion, the Medrash means that the source of the techeiles was concealed and it is only to be revealed in the future at a time when Hashem again wants us to wear it.

Other poskim disagree and contend that we should still attempt to fulfill the mitzvah of wearing techeiles on the tzitzis. They explain that the Medrash means that techeiles became unavailable. Rav Herzog zt”l, who followed this approach, speculated that persecution by anti-Semitic governments ended the production of techeiles. Still another possibility is that the knowledge how to produce the techeiles was lost, or that there was no longer availability or access to the chilazon, the source of the techeiles.

The Radziner Rebbe’s research

In 5647 (1887), the Radziner Rebbe, Rav Gershon Henoch Leiner, zt”l, published a small sefer, Sefunei Temunei Chol, wherein he discusses the importance of fulfilling the mitzvah of wearing techeiles even today. In his opinion, the Medrash quoted above means that techeiles became unavailable. The Radziner encouraged wearing something that might be techeiles even if it is uncertain that one is fulfilling the mitzvah. In his opinion, one who is wearing questionable techeiles should do so, because he may be fulfilling a mitzvah min hatorah. Thus, he contended that if he could identify a species that might be the chilazon, and he could extract a dye from it, one should wear tzitzis that are dyed with this product.

The Radziner himself analyzed every place in the Gemara where the word chilazon is mentioned, and defined what characteristics would help us identify the chilazon. Based on his analysis, he drew up a list of eleven requirements by which the chilazon used for techeiles can be identified. Among other requirements, these included that the chilazon would be located in the eastern Mediterranean Sea; that it is a marine animal and not a fish; that it must be able to live on land, at least for a brief period of time; that it produces a black ink and that it must have fins, bones, and sinews. The Radziner concluded that if one located a marine animal that meets all eleven requirements, one can assume that it is the chilazon.

Having completed his halachic research, the Radziner then began his scientific research to identify the chilazon. He traveled to Naples, Italy, the location of a major aquarium and marine research institute, to study marine animals that would meet all the requirements of techeiles. In Italy, he decided that the cuttlefish, which in many languages is called an inkfish, is indeed the chilazon from which one produces techeiles. The cuttlefish meets every one of the Radziner’s requirements for chilazon, including that it emits a dark dye, which is the reason why it is called an inkfish. The cuttlefish is not a true fish and is capable of living on land for brief periods of time.

The Radziner then published his second volume on the subject, Pesil Techeiles, in which he announced his discovery of the chilazon and his proofs why the cuttlefish meets all the requirements of the chilazon. Subsequently, the Radziner published a third volume, Ein Hatecheiles, whose purpose was to respond to all the questions he had been asked concerning what he had written in his previous volumes.

Reaction to the Radziner’s proposal

Although the Radziner had presented his case in an extremely convincing manner, most of the Gedolei Yisroel did not support his theory. The Radziner attempted to convince the poskim of his era of the validity of his approach, particularly, Rav Yitzchok Elchonon Spector of Kovno, the Beis Halevi (then the rav of Brisk), Rav Yehoshua Kutno (author of Yeshuos Malko), the Maharil Diskin (who had been rav of Brisk and was living in official retirement in Yerushalayim), and Rav Shmuel Salant (the rav of Yerushalayim). None of these rabbonim accepted the Radziner’s proposal. Their reasons for rejecting his proposal are significant.

Rav Yehoshua Kutno and Rav Yitzchok Elchonon disagreed with the Radziner because they both held that the Medrash quoted above should be understood literally — techeiles has been placed in genizah until Hashem again wants us to observe this mitzvah. Rav Yehoshua Kutno suggests several reasons why this happened, which are beyond the scope of this article.

Others were opposed to wearing techeiles because of sources in the writings of the Ari and other mekubalim that we are not to use techeiles until the rebuilding of the Beis Hamikdash, bimheira beyameinu. The Radziner did not agree with their interpretation of these sources.

An additional objection was raised against the Radziner’s position that one should wear questionable techeiles since one might be fulfilling the mitzvah. This is based on the poskim who contend that one who places on a white garment blue tzitzis that are dyed with a dye other than techeiles is not yotzei the mitzvah of tzitzis. Therefore, it is preferable to wear white tzitzis if one is uncertain (see Rema, Orach Chayim 9:5).

There were also objections to the Radziner’s conclusions on other grounds. Some objected to his choosing a non-kosher species as the source of the techeiles, since there are early poskim who contend that the techeiles must come from a kosher species. This subject is an old dispute, which can be traced back to the time of the rishonim and early acharonim.

Others contended that the color of the Radziner’s techeiles was wrong, since Rashi seems to indicate that the color of techeiles is green. However, it should be noted that the word yarok that Rashi uses can also mean gold, yellow or blue, as indicated by numerous sources in Chazal and rishonim. (Many of the sources as to whether the correct color of techeiles is green, blue or black are discussed in the article by Dr. Zvi Koren, which I refer to later in this article.)

The Beis Halevi’s approach

The Beis Halevi took issue with the Radziner on the basis of mesorah, but there is a dispute as to exactly what was his objection. The way the Radziner quotes the Beis Halevi, his concern was that the species identified by the Radziner was well-known, and, if it indeed was the correct source, this mesorah should not have been lost.

Rav Yosef Dov Soloveichek of Boston, himself named for the Beis Halevi, wrote a different understanding of the Beis Halevi’s opinion. He contends that we cannot identify the chilazon on the basis of research. When the Torah requires a specific type or species to fulfill a mitzvah, one cannot fulfill this mitzvah without a mesorah that this is the correct object with which to perform the mitzvah. Attempting to identify the type or species on the basis of research, analysis, or proofs will not help; nothing can be substituted for mesorah. Thus, no matter how compelling the evidence is that a specific species is the chilazon of techeiles, one will not fulfill the mitzvah of wearing threads dyed with this color. When Eliyahu Hanavi returns as the precursor to the mashiach, he will identify for us the mesorah he received from his rabbei’im and thereby we will be able to identify the proper techeiles.

The Maharsham

There was one gadol who considered the merits of the Radziner’s position. The Maharsham, Rav Shalom Mordechai Schvadron, rav of Bruzan, wore a talis with the Radziner’s techeiles, although apparently he did so only in private. However, in the final result, only the Radziner’s own chassidim and some Breslever chassidim wore the techeiles that the Radziner introduced.

Rav Herzog’s research

More than twenty years after the Radziner’s passing, Rav Yitzchak Isaac Herzog (who became the first Chief Rabbi of Israel several decades later) researched the source for the techeiles. He wrote up this research as his doctoral dissertation.

In his analysis of the halachic issues involved, Rav Herzog accepted most of the Radziner’s opinions and interpretations. However, there are some aspects of the Radziner’s approach with which Rav Herzog took issue. Whereas the Radziner assumed that every place in the Gemara where it refers to chilazon, it means the chilazon that was used in making techeiles, Rav Herzog assumes that chilazon means a sea snail, and not necessarily the snail used in making the techeiles. (By the way, in Modern Hebrew, Ben Yehudah decided to use the word chilazon for snail, rather than the original Hebrew word, shavlul.) Thus, in Rav Herzog’s opinion, not all of the Radziner’s requirements in determining the species for the techeiles are accurate. Therefore, Rav Herzog focused on analyzing the numerous species of sea snails for the most likely candidate to produce techeiles.

Rav Herzog took issue on one major point of the Radziner’s research. Rav Herzog took samples of the dye recommended by the Radziner as techeiles and had them chemically tested. Based on results that he received from the laboratories, Rav Herzog concluded that the blue color that results from the Radziner’s method of producing techeiles is not caused by anything in the cuttlefish ink. The chemists he consulted contended that the color is an artificial dye named Prussian blue, which is created by the chemicals added as part of the processing. In Rav Herzog’s opinion, since he could not discern anything in the cuttlefish that causes the blue coloring, he reached the conclusion that the cuttlefish is not the source of the techeiles. There are answers how the Radziner might have responded to this concern, but it is inappropriate for others to speak on his behalf.

In his dissertation, Rav Herzog analyzed various sea snails, concluding that none of them fit as sources for the techeiles. Apparently, decades later, Rav Herzog was still grappling with which species might be the correct source.

It should be noted that all the poskim who disagreed with the Radziner’s proposal would disagree with Rav Herzog’s proposals – the reasons that they rejected the inkfish would also apply to a sea snail.

Many scientific researchers have suggested that the species of sea snail currently called Hexaplex trunculus might indeed be the source for techeiles. (Since most people who write on this topic usually refer to this species by its earlier name, Murex trunculus, I will use the latter term.) It is curious that this is one of the species of sea snail that Rav Herzog considered. Most people who today have their tzitzis dyed blue are using an indigo color derived from Murex trunculus.

Nevertheless, there are strong technical objections to this. Some of these arguments might be resolved based on a brilliant article published recently by Professor Zvi Koren in Tradition. However, in Professor Koren’s opinion, both the method used to extract dye from Murex trunculus and the color used is erroneous, and is certainly not the proper color of techeiles.

We note that the method currently used to process the dye from the Murex trunculus cannot be the correct method of dyeing techeiles threads, as performed by our ancestors, for the following reasons:

  1. The current method of extracting dye from Murex trunculus involves removing a gland from the snail, which would involve the melacha of gozeiz, removing part of a living creature. (According to many poskim, one violates this also by removing part of a creature that has died.) Clearly, this could not have been the method of removing the dye from chilazon in earlier days, as can be proved from the Gemara (Shabbos 75a), since no mention is made of this prohibition in the Gemara, although it mentions other prohibitions that are transgressed in the capture and processing of the chilazon on Shabbos.
  2. Another objection is based on the fact that it can be demonstrated from the Gemara that the removing of the dye liquid from the chilazon kills it, although one would prefer that the chilazon remain alive for as long as possible. However, in the process used to remove the dye from Murex, the snail can remain alive for several hours after the process is complete.
  3. A third problem with the current method of using Murex trunculus dye requires an introduction. At the time of the Gemara, there were unscrupulous individuals who sold threads dyed with a coloring called kla ilan. This coloring is not kosher as techeiles, and someone wearing it on his tzitzis would not fulfill the mitzvah of wearing techeiles. According to the Aruch, kla ilan is indigo, a vegetable dye that has a blue color. Thus, the Gemara was concerned about someone selling indigo-colored threads as techeiles threads to an unsuspecting buyer. The Gemara describes a test that can be used to check whether the threads are kla ilan or techeiles, by testing the threads for colorfastness: kla ilan would fade, whereas techeiles would remain fast. However, the dye used currently by Murex trunculus enthusiasts is chemically identical to indigo. How, then, can a chemical test for colorfastness be used to determine what was the source of the indigo?
  4. The Rambam describes that the “blood” that is the source of the techeiles is black when removed from the chilazon. The gland extract removed from Murex trunculus is clear when it is removed and changes color afterwards.

Obviously, I am not the first one to note these difficulties with the process of extracting dye from Murex trunculus. However, the responses I have seen to answer these questions are very tenuous.

We see that there has been a significant amount of research about the source of techeiles and the possibility of fulfilling this mitzvah in our day. Due to the above mentioned considerations, those who follow the approach of the majority of the poskim of earlier generations and wear only white tzitzis have a substantive basis in halacha.