It is a layer of ice
and diamonds.
Deep silver glass
covered with wire. 
When the cold is cold
but still liquid and reserved
for hearts of olives, intangible
in keeping with logic.

From page 53 of The Complete Guide to the Art of Modern Cookery by Auguste Escoffier, translated by H. L. Cracknell and R. J. Kaufmann (John Wiley & Sons, Inc. 1979).