Species evolve exactly as if they were adapting as best they could to a changing world, and not at all as if they were moving toward a set goal.

The search for historical laws is, I maintain, mistaken in principle.

Most of the dogmatic religions have exhibited a perverse talent for taking the wrong side on the most important concepts in the material universe, from the structure of the solar system to the origin of man.

Almost all paleontologists recognize that the discovery of a complete transition is in any case unlikely.

The earliest and most primitive known members of every order already have the basic ordinal characters, and in no case is an approximately continuous sequence from one order to another known. In most cases the break is so sharp and the gap so large that the origin of the order is speculative and much disputed.

A rill in a barnyard and the Grand Canyon represent, in the main, stages of valley erosion that began some millions of years apart.

The science of systematics has long been affected by profound philosophical preconceptions, which have been all the more influential for being usually covert, even subconscious.