A most intriguing problem of hue

The purple dye which has been used since antiquity as the mark of wealth and lavish opulence, is so well known that it virtually signifies "royalty" and the trappings of kings of the realm. The Greeks obtained it, drop by drop, squeezed from the mollusks Murex Trunculus and Purpura Haemastoma which are found along the eastern Mediterranean shores near Tyre, whence the common name Tyrian Purple.

The color is striking, once seen is it hard to forget or confuse with any other hue. A similar murex is found in the Caribbean waters, and the dye is often used to trim Mexican basketware, found in shops and yard sales throughout the States. I can vouch for the similarity of color between the modern Mexican and ancient Mediterranean samples, for a curious personal reason. Years ago when visiting Crete, I stopped at the small museum at Chanea at western end of the island, and noticed a jar which has a crust of bright purple around the mouth. A small bit had fallen off which I picked up and put in my wallet, years later I held this up against a sample of Mexican basketware and the color was an exact match. The New World murex is larger and yields more colorant, but the hue of its material is identical with my ancient sample.

But back in Greece, I remembered Homer's striking figure of the "purple sea" (porphurea thalassa), which had always puzzled me as a student. And equally odd was his "purple blood" gushing forth, and even a "purple rainbow" mentioned once in the Iliad. Our sense of the color "purple" does not fit these uses, it was clear to me even then that something was wrong with our color-sense, or that colors can shift as part of the process of social evolution. Yet all these three uses are by the same author and the identical time-frame, so I left Greece that summer puzzled and intrigued.

About that time a well known scholar tendered the opinion that "porphureos", which was used by Aeschylus in the gory death scene in which Clytemnestra hacked open her husband' s head so that the "purple blood" gushed forth. A late Byzantine glossator had suggested that blood when dried was a darkish brown, and the bookish Classicist followed his late source without hesitation. But that led to worse problems, for how could Homer's sea be brownish, or a rainbow be rusty?

Before leaving Greece I held up my micro-sample one day at eye level and sighted beyond it to that wonderful Mediterranean sea. I saw right off that both the flake and the sea were iridescent, it was that quality of inner shinning-ness which has made the Mediterranean waters so famous to century after century. And the Murex had somehow chanced upon the same iridescence, so it was the relative scale of iridescence which was behind these word-usages.

Of course the rainbow with its prismatic splitting of the mixed hues of light, is iridescent. It is fitting that at the end of Vergil's fourth books of the Aeneid that it is the goddess Iris descending in a glowing rainbow to mark Dido's death. This diffraction of light into its spectral components also makes the bluejay's feathers so bright and unmistakable,dependent on the minute grid size of each feather which captures one portion of the light source. But purple blood was still unclear until I saw a cut artery spurting bright, iridescent aerated blood in a film record of heart surgery. Arterial blood has that bright, shining quality too, and so the circle of the bright purple associations was finally closed to my satisfaction.

Two points can be made from this investigation:

First that notions of color are not absolute even in a given time-frame, much less over the course of centuries. Colors and the words we use to denote them can change, especially when new hues like the aniline dyes elicited from lowly coal-tar in the mid l9th c. change our color-susceptibilities.

Second, if we examine color in terms of its performance in light and its origin in the world of living organisms, we can establish identities much more exactly that through the historical written record. In short, using eyes to see with and a modest touch of imagination, one can open doors to the ways hues were seen in other times and places.

William Harris
Prof. Em. Middlebury College