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.

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.

The fact -- not theory -- that evolution has occurred and the Darwinian theory as to how it occurred have become so confused in popular opinion that the distinction must be stressed.

The opposition to teaching evolution is, of course, almost always given a religious reason. That may usually be its real basis, but I think it is often a mask, perhaps unconscious, for underlying anti-intellectualism or antiscientism.

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.

Recognition of this kinship with the rest of the universe is necessary for understanding him, but his essential nature is defined by qualities found nowhere else, not by those he has in common with apes, fishes, trees, fire, or anything other than himself.

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