Home >> PUBLICATIONS IN ENGLISH >> "Enigma of the Septuagenian Murex", 2009 >> Abstract
Irving I. Ziderman
  Abstract of lecture presented at the 28th Annual Meeting on Dyes in History and Archaeology, in  Poznan, Poland, on 22nd October 2009
Purple dyes from Mediterranean murex shellfish were among the most precious treasures of antiquity. There were two types. Tyrian purple (biblical argaman) was made from spiny dye-murex (Bolinus brandaris), often in admixture with rockshell (Stramonita haemastoma); chemically, it is 6,6’-dibromoindigotin. Hyacinth purple (biblical tekhelet) had a bluer shade than Tyrian purple, giving violet-blue colours, and was made from banded dye-murex (Hexaplex trunculus); it is a mixture of dyestuffs, largely 6-monobromoindigotin and indigotin.
Amongst the characteristics specified in the Talmud for recognizing the shellfish (Hebrew hilazon) used for dyeingtekhelet, one of the four points listed there has hitherto escaped satisfactory elucidation: it is - ‘ascends (or goes up) once in seventy years’ (Menahot 44a). A literal meaning would imply a life-cycle lasting seventy years; but the Talmud does not state the year from which to reckon the anniversary. In fact, such longevity is unknown in the mollusk world, including H. trunculus. Moreover, there is no historical indication of this periodicity in regard to the ancient hyacinth-purple-dyeing craft. Indeed, it is implausible that, throughout its 3,000 year-long history, such a widespread manufacturing industry was dependant on supply of its essential raw material becoming available just once in seventy years.
Therefore previous authors have been constrained to regard the Talmudic enigma as hyperbole, merely indicating that the creatures reappeared intermittently: so ‘once in seventy years’ may perhaps be just a metaphoric allusion to the renowned infrequency of Halley’s comet. Accordingly, Herzog (1913) rejected H. trunculus as the source of ritual tekhelet because it appeared to lack such rarity. Some alternative Talmudic texts have ‘seven’ instead of ‘seventy’; consequently, Spanier and Ziderman (1982) associated a cycle of seven (months) with the biannual seasons for H. trunculus fishing.
Thus it is not surprising that Maimonides’ authoritative Code of Judaic law (1178) makes no mention of the enigmatic phrase, even though the other three characteristics from the Talmud are duly recorded there (Zizith 2:2). However, the Code does add there a novel fourth characteristic of tekhelet’s shellfish - ‘It is to be found in the Salt (=Mediterranean) Sea’, a phrase hitherto considered to be merely an innovation of Maimonides, it not being taken from the Talmud.
It is now proposed that Maimonides considered the Talmud’s ‘ascends once in seventy years’ to mean that the murex never ascends out of the sea, but is to be found only in the Mediterranean, whence it must necessarily be fished despite the dangers involved.