“There is an obligation upon all who are
capable, to search for [tekhelet], to merit
(Rabbi G. E. Leiner, the Radzyner Rebbe)
The Bible in the book of Numbers relates God’s charge to Moses:
to the children of
This passage, part of the kriyat shema prayer complex, is recited twice daily by observant Jews who till this day can be seen with fringes - tsitsit - dangling from their prayer shawls. The eleventh century Biblical commentator, Rashi, explains how looking at the fringes reminds one of all God’s commandments. The word tsitsit - fringes - is numerically equivalent to 600. Tsitsit are traditionally tied with eight strings and five knots for a total of 613 - the number of commandments in the Torah. Linguistically, however, the subject of the sentence - that which is to remind us of God’s commandments - is not the tsitsit, but rather the thread of blue, the tekhelet.
The secrets of the tekhelet color, its source and method of manufacture have been lost for over 1300 years. As a result, many of the laws pertaining to its use have been deemed “academic”, and their study was, to a certain extent, neglected as compared with the more prosaic statutes. What is the significance of the blue thread and why has this commandment fallen into disuse?
Over the past few years, there has been an increasing awareness and renewed discussion regarding the Biblical dye tekhelet. In this article, I would like to survey the history of the search for tekhelet and describe the recent advances in our understanding of the topic in light of archeological, chemical, and biological findings.
Tekhelet in the ancient world
One of the
earliest recorded mentions of tekhelet is in the Tell-el-Amarna
Tablets (1500-1300 BCE). subâtu sâ takílti - a garment of tekhelet -
is listed as one of the precious articles sent to
From the start,
the colored garments were greatly revered, as can be attested to by a Minoan
priestess figurine dated 1600 BCE which has what appear to be dark blue
decorations on her attire.5 The dyes were rare and
valuable, and wool colored with them was worth up to 20 times its weight in
These precious dyes were reserved for royalty; they colored the robes of the
kings and princes of Media,
Moreover, the ancient scholars write about these dyes in great detail. Pliny and Aristotle describe the snails, how and where to find them, and the procedure for dyeing with them. Vitruvius mentions that there is a connection between the varied colors (purple through blue) obtainable from the snails and differing degrees of sunlight to which they are exposed. “For it does not yield the same color everywhere, but is modified naturally by the course of the sun... As we proceed between the north and west it becomes a leaden blue.” Scholars have positively identified these shells (purpurae and bucinae in Pliny’s terminology) with the mollusks Murex trunculus, Murex brandaris, and Thais Haemastoma.
By the time of
the Exodus from
Tekhelet was worn by nobility and priests throughout the ancient world. It is found in those contexts within the Bible as well; it adorns the Tabernacle and comprises the special clothes of the high priest. On this basis Professor Jacob Milgrom has suggested an explanation of the significance of the blue thread on the Jew’s garments.
is the epitome of the democratic thrust within Judaism which equalizes not by
leveling but by elevating: all of
Talmudic descriptions of tekhelet and the hillazon
Aside from the
secular references, Jewish sources have maintained a tradition as to the
nature of tekhelet, and its marine source, the hillazon. Though
there is some confusion as to the precise hue of the dye,
one authority’s charming, if not totally convincing proof deserves mention:
“the simple tradition in all of
The Talmud relates that due to the extreme scarcity of tekhelet, avaricious individuals introduced a counterfeit dye, kala ilan, obtained from a much cheaper vegetable source. This fraudulent counterpart provides the most direct demonstration of tekhelet’s color. The Talmud states that it was absolutely impossible to outwardly distinguish between true tekhelet and kala ilan, - consistently identified as indigo - which is the color of a clear sky.
Perhaps the most important characteristic of the tekhelet dye was that it was steadfast in color. Maimonides writes that “its dyeing is well known for its steadfast beauty and does not change.”
Jewish sources have also described the source of the tekhelet - the marine organism called the hillazon. One must be careful not “[to huddle up] all references to the hillazon as applying exclusively to the tekhelet-hillazon.” Indeed, hillazon in modern Hebrew is used to describe all kinds of snails, both land and sea species. This having been noted, a portrait of the hillazon can, nonetheless, be surmised.
was found along the Northern coast of
The suppression and eventual demise of the Jewish tekhelet industry
Due to the lucrative nature of purple and blue dyeing, and the status associated with wearing garments colored with those dyes, control over the dye industry was always coveted and often a source of tension. It has been suggested that the war between the Caananite general Sisera, and the Israelites led by Deborah recorded in Judges 4-5 were over this issue. During the Roman period the contention reached its climax as the dye industry slowly came under imperial control. Caesar and Augustus restricted the use of the dyes to governing classes. Nero (d. 68 CE) issued a decree that gave the emperor exclusive right to wear purple or blue garments. Under Constantius (337-362) the restrictions were slackly enforced. In 383, an edict by Gratian, Valentinian, and Theodosius deemed the manufacture of higher quality purple and blue a state monopoly.
Hints of the
political complications associated with tekhelet are echoed within the
Talmud and Medrashim. It seems clear that
beginning of the sixth century, tekhelet was still being brought from
The search for the ancient dye by secular scholars
Rondelet (d. 1566) was the first to identify Pliny’s purpura with the
species Murex brandaris,
and Fabius Columna in 1616 further suggests Murex trunculus as having
been utilized in the ancient dyeing process.
In 1685, William Cole noted that a colorless fluid in the hypobranchial gland
of marine mollusks (Purpura lapillus) found off the coast of
The search for tekhelet by Jewish scholars
mid-19th century, the issue of tekhelet began to surface among Jewish
writers. (It should be noted that the secular research on this topic was as
yet unknown to the rabbinic community.) Along with the renewed
Messianic interest and questions regarding the rebuilding of the
The new tekhelet was not widely accepted by the general rabbinic world. The Radzyner wrote two more books, P’til Tekhelet and Eyn Hatekhelet, to explain his ideas and to counter opposition from other rabbis. These books still stand as the definitive works on the subject, and form the legalistic foundation for any discussion on the topic.
In 1913, Rabbi Isaac Herzog, then Chief Rabbi of Dublin and later the first Chief Rabbi of the State of Israel, as part of research towards his doctoral thesis, sent samples of the Radzyn tekhelet to leading chemists and dye experts in Germany, France and England for analysis. The results that he received were surprising. The experts determined that the blue dye of Radzyn was not organic in nature, but rather was the inorganic dye known as Prussian Blue, or ferric ferrocyanide. Herzog refused to believe that the Radzyner Rebbe would have purposely misled his followers and wrote to the dye masters of Radzyn asking for their process. Upon investigation, the solution to the riddle became apparent. The Radzyn recipe called for heating the squid ink to very high temperatures and then for the addition of iron filings. What in fact happens under these conditions is that the organic molecules break down and the constituent atoms of carbon and nitrogen recombine with the iron, yielding Prussian Blue dye. The squid ink is not an essential component for this reaction; any organic substance could be substituted, since the structure of the molecule is irrelevant and only the elemental components are utilized. Herzog could not accept the notion that the Talmudic requirement for a specific marine source, the hillazon, could be based on such an indirect and vague relationship. He therefore concluded that the Radzyn tekhelet could not be considered authentic.
interesting side note of history, during World War II with the destruction of
East European Jewry, the tekhelet factories of Radzyn were ruined and
the process lost. When the survivors of Radzyn made their way to
Herzog himself was unable to come to a definite conclusion regarding the hillazon. Virtually all of his doctorate deals with the snails from the Murex family, showing how the consensus among the scientific community is that they (trunculus in particular) were the source of the tekhelet dye. “Of the species known to have been used by the Phoenicians in purple-dyeing, the one which furnishes a dye answering at least to some extent to the tradition of the tekhelet nuance is none other than the Murex trunculus.” Herzog shows conclusively that these mollusks were used in ancient times for dyeing blue, and he notes the difficulty with the contention that Jewish tekhelet came from some marine animal different than that used by the entirety of the ancient world, an organism that was unknown to the ancient scholars, and has left no archeological evidence. Herzog admits that “it is very unlikely that the tekhelet-hillazon is not the snail called Murex trunculus, but though unlikely, it is still possible.”
Despite the overwhelming proof, Rabbi Herzog was unable to categorically identify the hillazon with the trunculus, for a number of reasons. First, he felt that trunculus did not fit the Talmud’s description of domeh l’yam - having the appearance of the sea. In fact, however, Herzog had seen only specimens cleaned and polished. In that state, the shells are colored with brown and white bands. Trunculus found in the ocean, on the other hand, are covered by small organisms whose texture and color varies from place to place, but the same sea-fouling will be found on all the rocks and shells in each region. Sometimes the coating has a blue or green coloring, and this would fit the description as similar to the sea. Moreover, since the word yam in Biblical and Talmudic Hebrew also means “sea bed”, perhaps the hillazon is being portrayed as similar to the surrounding landscape, which is a perfectly fitting representation of the trunculus in its natural habitat.
Second, trunculus has no periodic cycle corresponding to seven or seventy years. Herzog admits that “Science knows nothing of such a septuagenerian ‘appearance’ of any of the denizens of the sea.” Maimonides does not mention the periodical appearance of the hillazon, which has led commentators to conclude that he did not consider this an essential characteristic of the animal.27 Indeed both he and the Radzyner Rebbe deal with this particular criterion of the hillazon. They raise the possibility that the cycle refers to periods of greater or lesser availability or accessibility, but that the animal itself is always obtainable.
Third, Herzog was under the impression that the dye obtained from the trunculus was not a steadfast one. Modern dye experts disagree with this and contend that both indigo and dibromoindigo do indeed bind tightly to wool and are among the fastest natural dyes. Though indigo is not known to be a particularly enduring dye, this is true only of cotton dyed indigo. Both dibromoindigo (purple) and indigo, however, bind very tightly to wool and will neither rub out nor fade over time. Prof. Otto Elsner, a leading dye expert, has asserted that these dyes were among the fastest dyes available to the ancient world. Our own experience has shown that strings dyed with trunculus blue have maintained their color through daily wear and periodical washing for more than ten years.
The fourth, and most substantial problem that Herzog had with trunculus, was that the dye obtained from that snail produced a blue-violet color, and not the sky-blue hue traditionally associated with tekhelet. This issue was really the core of the difficulty in identifying the hillazon with the trunculus. “However”, Herzog writes, “if we unequivocally determine that the appearance of tekhelet had no violet (purple) component, then this would be enough to dislodge [disprove] the assertion that [Murex trunculus is the hillazon].”
another candidate for the hillazon - the snail Janthina. Though
he had never dyed with that snail, the fact that the shell had a violet color
fit well with the description of being similar to the sea. Modern research,
however, has shown that Janthina could not have been used in any
dyeing industry. It lives in floating colonies and washes up on the shores of
The science of tekhelet
In the early
1980’s while researching ancient dyeing techniques, Otto Elsner of the
Shenkar College of Fibers in
The chemistry and bio-chemistry of the dyes can be summarized as follows: Inside the hypobranchial gland of the snail, only the precursors to the dye exist as a clear liquid. (The indigo molecule contains a substance called indole, also found in the intestines of animals, which is a waste product of the proteins that constitute most of meat. Indole is a poison and does not pass out of the body directly. In order to remove it, animals unite it with sulfur, and this harmless combination is excreted through the kidney. Murex snails incorporate bromine and potassium, in addition to sulfur, to neutralize the indole and the resultant molecules become the dye precursors.) When the precursors are exposed to air and sunlight in the presence of the enzyme purpurase which also exists within the gland, they turn into the dye material. Purpurase quickly decomposes, so in order for this reaction to take place, the gland must be smashed soon after being taken from the live snail, (in accordance with the Talmudic passage that the tekhelet is taken from the hillazon while still alive). In the trunculus, these reactions result in a mixture of dibromoindigo (purple) and indigo. The dye must be put into solution (usually accomplished by reducing the dye molecule) in order for them to bind tightly to wool. In this state, if dibromoindigo is exposed to ultraviolet light, the bromine bonds will be broken and it will transform to indigo, turning the trunculus colorant from purplish-blue to pure blue. (It should be noted that the blue dye obtained from Murex trunculus is molecularly equivalent to indigo the Talmud’s counterfeit kala ilan. If trunculus dye may not be used for tekhelet, then, as Herzog argues, the Talmud would have had to assert that not only is kala ilan unacceptable, but even tekhelet obtained from some marine animals - namely the Murex - is also unsuitable for the mitzvah, since the two dyes (kala ilan and Murex blue) are equivalent.)
Over the last few decades, much work has been done to reestablish the tekhelet dying process. Dr. Irving Ziderman, from the Israel Fiber Institute has published a number of articles describing the scientific aspects and religious implications of the Trunculus dye. Rabbi Herzog's doctorate has finally been published after nearly 80 years, while Rabbi Menakhem Borstein has published a book surveying the relevant Jewish legal aspects of tekhelet. Prof. Tzvi Koren from the Shenkar College of Fibers has done rigorous chemical analysis of the dye from present day snails as compared with samples from archeological artifacts dating back to 3500 BCE. But until a few years ago, the knowledge had remained mainly in the laboratory and the library.
In 1985, Rabbi
Eliahu Tevger of
 Numbers, 15; 38-39
 Rashi on Numbers, 15; 39. Nachmanides proposes that when one gazes upon the blue string he is reminded of the sea and sky and ultimately of God and all His commandments.
 So, for example, instead of ruling on a certain debate, R. Yosef Kara, declares: “It would appear that we should not pay regard to this argument since it makes no difference at this time [since the tekhelet is no longer available].” (Bet Yosef, Hilkhot Tsitsit, O.H. 11)
 Mercer, Samuel A.B., The Tell El-Amarna Tablets, Macmillan, 1939, Presents from Tusratta to Amenophis III, p. 85 line 18, 29, 36.
 Stieglitz, Robert R., “The Minoan Origin of Tyrian Purple”, Biblical Archaeologist, 57:1 (1994) pp. 46-54.
 McGovern, P.E. and Michel, R.H. Anal. Chem. 1985, 57, 1514A-1522A.
 Pritchard, J.B. Recovering
 Karmon, Nira,
 Pollux, J., Onomasticon 1.45-48.
 Pliny the Elder, Natural History, Book IX, LX-LXV.
 Aristotle, De Animalibus Historia, p. 175.
 Vitruvius. De Architectura, Libr. VII, ch. 13.
 Esther 8; 15
 Ezekiel 27; 7
 Milgrom, J., “The Tassel and the Tallit,” The Fourth Annual Rabbi Louis Fineberg Memorial Lecture (University of Cincinnati, 1981).
 Some of the confusion may come from differences in color designation between modern and classical terminology. For example, Rashi on Shemot 25;4 writes regarding tekhelet, “and its color is green”, while on Bemidbar 15;41he comments, “and so the color of tekhelet resembles the color of the darkened sky at dusk.”
 Herzog, I, Kol Kitvei, Orach Haim siman 8, page 59.
 Menachot 43b, Hulin 89a, Sota 17a, Y. Berakhot ch 1 hal. 2, Sifre Bemidbar 15;38, Medrash R. Naso 14;3, Medrash R. Shelakh 17;5, Medrash Tehlillim Mizmor 24;9 and 90;10, and Yalkut Shimoni Tehillim 90.
 Rav Kapakh’s version, Shemot 25;4, p. 71 n. 2.
 Hil. Tsitsit 2;1.
 Bava Metzia 61b, “The Holy One Blessed be He said: I have distinguished between the drop of [semen that was to become] a firstborn and that of a non-firstborn, I will exact retribution on he who attaches kala ilan to his cloth and claims it is tekhelet.”
 Aruch on the word kala ilan, Yad, Tsitist 2;1 and Rav Kapakh’s comments, Herzog, The Royal Purple, p. 94-96.
 Yad, Hil. Tzitzit, 2;1.
 Herzog, The Royal Purple, p. 60.
 Shabbat 26a
“Between the ladders of
 Devarim Rabba par. 67;11, Shabbat 85a.
 Shabbat 85a and Rashi ad loc.
 Menachot 44a.
 Once in 70 years (Menachot 44a) or once in 7 years (Masechet Tzitzit hal. 21). See Rav Borstien Hatekhelet, page 38 footnotes 76 and 77. Also, Rav Herzog in Kol Kitvie page 52.
 Note R. Eliyahu from Vilna claims that the Rabbis term anything in the sea “fish”. (Eliyahu Rabba, Kelim 10;1)
 “And we learn in the Jerusalem Talmud, between tekhelet and karti - between prophira and prifinin. It is a garment that is called porphyra in other languages.” (Ra’avyah commentary to Berakhot 9a siman 25).
 The northern coastal tribes were involved in that war, and Sisera’s mother expects of her son, “to Sisera a booty of divers colors, a plunder of many colored needlework, dyed double worked garments for the spoilers.” (Judges 5;30).
 Seutonius, Vita Caes, p. 43, Dio Cassius, bk XLIX, p.161.
 Vita Neronis, p. 32.
 Herzog, The Royal Purple, pp. 107-113.
 Baker, J.T., “Tyrian Purple: an ancient dye, a modern problem”, Endeavour, 33, (1974) pp. 11-17.
 Menachot 42b see also Menachot 43a
 Medrash Raba Beraishit 85;9.
 Sanhedrin 12a
 Chulin 59b
 Tanhuma, parashat Shelakh.
 Herzog, The Royal Purple, p. 114.
 Lamarck, Jean
Baptiste, Systéme des Animaux
 Columna, F. Opusculum
 Cole, W., Philos. Trans. R. Soc. London, 1685, 15, 1278-1286.
 de Lacaze-Duthiers, H. Ann. Sci. Nat., Zool. Biol. Anim. 1859, 4th series 12, 5-84.
 Friedländer, P., Ber. Dtsch. Chem. Ges., 1909, 42, 765-770.
 Bouchilloux, S.
and Roche, J. Bull. Inst. Océanogr.
 Kupat HaRochlim, found in the Tefferet Yisrael’s introduction to the order of Moed.
 Herzog, The
Royal Purple, 114-118; Herzog, The Dyeing of Purple in Ancient
 Herzog, The Royal Purple, p. 73.
 Herzog, Hatechelet Byisrael, 5;1, in Rav Borstien’s book "äúëìú", p. 421.
 See for example Isaiah 11; 9 “as the waters cover the yam.”
 Tevger, E., Kelil
Tekhelet, Chemed Press,
 Herzog, The Royal Purple, p. 69
 Herzog, Kol Kitvei, Orach Hayyim, 7; 50-52.
 R. Leiner, Sefunei Temunei Chol p. 4.
 in a personal correspondence.
 Herzog, Hatekhelet BiYisrael, ch. 11 “Is the Murex Trunculus the Hillazon of Tekhelet?”, found in R. Borstein’s book Hatekhelet, p. 224.
 H.K. Mienis and
 Fox, H.M., Blue
Blood in Animals, Routelidge & Kegan Paul,
 Herzog, The Royal Purple, page 73. Rav Herzog finds this proof for the identification of the hillazon with trunculus irrefutable, but for one possible loophole. “Should the dye of the Janthina prove to be faster than that of the Murex trunculus,... then the tests [recorded in the Talmud] might well distinguish tekhelet dyed with Janthina from that dyed with M. trunculus.” Subsequent research done on Janthina has shown that not only is that dye not fast, but it is in fact not even a dye. The pigment is water soluble, does not bind to the wool, does not color the wool homogeneously, and stains the fabric brown and not blue. (See the article by H.K. Mienis and E. Spanier, “A review of the Family Janthinidae (Mollusca, Gastropoda) in Connection with the Tekhelet Dye,” The Royal Purple, p. 197.) With this loophole eliminated, Rav Herzog’s original argument remains conclusive. In fact, the Radzyner anticipated this argument. See Sefunei Temunie Chol, p. 19.