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

...the argument from absence of transitional types boils down to the striking fact that such types are always lacking unless they have been found.

It is inherent in any definition of science that statements that cannot be checked by observation are not really saying anything or at least they are not science.

Man stands alone in the universe, a unique product of a long, unconscious, impersonal, material process with unique understanding and potentialities. These he owes to no one but himself, and it is to himself that he is responsible. He is not the creature of uncontrollable and undeterminable forces, but is his own master. He can and must decide and manage his own destiny.

The meaning that we are seeking in evolution is its meaning to us, to man. The ethics of evolution must be human ethics. It is one of the many unique qualities of man, the new sort of animal, that he is the only ethical animal. The ethical need and its fulfillment are also products of evolution, but they have been produced in man alone.

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

It remains true, as every paleontologist knows, that most new species, genera, and families, and that nearly all categories above the level of families, appear in the record suddenly and are not led up to by known, gradual completely continuous transitional sequences.