"Now such a minimal list of such maximal centrality and importance bears a description in ordinary language -- but its proper designation requires that evolutionary biologists utter a word rigorously expunged from our professional consciousness since day one of our preparatory course work: the concept that dare not speak its name -- essence, essence, essence (say the word a few times out loud until the fear evaporates and the laughter recedes). It's high time that we repressed our aversion to this good and honorable word. Theories have essences. (So by the way, in a more restrictive and unanced sense, do organisms . . . .)"
Stephen Jay Gould, _The Structure of Evolutionary Theory_, p. 10
Carrol