H. Tekhelet and the Colour of the Sea
The different recensions of R. Meir’s saying call for careful study. We shall start first with (a) and (b). It is remarkable that in these as indeed in all the other recensions excepting (f) the comparison is instituted, contrary to expectation, not directly with the sky but first with the sea (yam) and through it with the sky. Before attempting to account for this phenomenon we should try to gain a clear conception of the significance of yam in this connection.
The colour of the sea is not the same all over. Here, however, the reference is undoubtedly to the Mediterranean, or rather to the Mediterranean off the Syrian and Palestinian coasts. The study of the colours of the various seas is but of recent growth. The matter is adequately treated by O. Krümmel in his textbook of Oceanography. In the latest edition of the British Encyclopaedia there is a very good article on the subject: “The colour of ocean water far from land is an almost pure blue, and all the variations of tint towards green are the result of local disturbances:
“The usual cause is turbidity of some kind and this in high seas is almost always due to swarms of plankton. The colour of sea water as it is seen on board ship is most readily determined by comparison with the tints of Forel’s Xanthometer or colour scale which consists of a series of glass tubes fixed like the rings of a ladder in a frame and filled with a mixture of blue and yellow liquids in varying proportions.
“For this purpose the zero, or pure, blue is represented by a solution of one part of copper sulphate and 9 parts of ammoniac in 190 parts of water. Observations with the Xanthometer have hitherto not been numerous, but it appears that the purest blue (0-1 on Forel’s scale) is found in the Saragasso sea, in the North Atlantic and in similarly situated tropical or sub-tropical regions, in the India and Pacific Oceans. The Northern seas have an increasing tendency towards green, the Trimingen sea showing 5-9 Forel, while in the North sea the water is usually a pure green.
“The blue of the sea water as observed by the Forel scale has, of course, nothing to do with the blue appearance of any distant surface due to the reflection of a cloudless sky.1 Over shallows even the water of the tropical oceans is always green. There is a distinct relationship between colour and transparency in the ocean; the most transparent water which is the most free from plankton is always the purest blue while an increasing turbidity is usually associated with an increasing tint of green. The natural colour of pure sea water is blue and this is emphasized in deep and very clear water which appears almost black to the eye… The greatest transparency hitherto reported is in the eastern basin of the Mediterranean where J. Huksch found the disk visible as a rule from 2 to 7 fathoms, and off the Syrian coast even to 33 fathoms.”2 Combining now the two statements: (1) that the greater the transparency the deeper is the blue, and that (2) off the Syrian coast the greatest transparency has been reported; we at once obtain the result that Tekhelet was very much like the deep blue of the Mediterranean along the Palestinian coast. The assertion תכלת דומה לים (Tekhelet is like the sea) scarcely however warrants absolute identity of colour. The verb damah דמה “to be like” is elastic enough, although by no means excluding absolute likeness. Where absolute identity of colour is insisted upon, the Mishnah employs the Kaph-comparationis.3 That such is not the case here is, however, on the other hand, no indication as to the contrary. R. Meir’s object in this instance, be it duly emphasized, is not to give a definition of Tekhelet but merely to explain its symbolic significance.