It has sometimes been said that the success of the Origin proved "that the subject was in the air," or "that men's minds were prepared for it." I do not think that this is strictly true, for I occasionally sounded not a few naturalists, and never happened to come across a single one who seemed to doubt about the permanence of species.

Charles Darwin's Works: The life and letters of Charles Darwin... ed. by his son, Francis Darwin. 2v (ed. 1896)