Do you see this egg? With this you can topple every theological theory, every church or temple in the world. What is it, this egg, before the seed is introduced into it? An insentient mass. And after the seed has been introduced to into it? What is it then? An insentient mass. For what is the seed itself other than a crude and inanimate fluid? How is this mass to make a transition to a different structure, to sentience, to life? Through heat. And what will produce that heat in it? Motion.

Conversation Between D'Alembert and Diderot, as quoted in Selected Writings (1966) edited by Lester G. Crocker, and The Enlightenment and the Intellectual Foundations of Modern Culture (2004) by Louis K Dupré, p. 30 - D'Alembert's Dream (1769)