There is no doubt that human survival will continue to depend more and more on human intellect and technology. It is idle to argue whether this is good or bad. The point of no return was passed long ago, before anyone knew it was happening.

The living world is not a single array... connected by unbroken series of intergrades.

Scientists often have a naive faith that if only they could discover enough facts about a problem, these facts would somehow arrange themselves in a compelling and true solution.

Natural selection must be replaced by eugenical artificial selection. This idea constitutes the sound core of eugenics, the applied science of human betterment.

Seen in retrospect, evolution as a whole doubtless had a general direction, from simple to complex, from dependence on to relative independence of the environment, to greater and greater autonomy of individuals, greater and greater development of sense organs and nervous systems conveying and processing information about the state of the organism's surroundings, and finally greater and greater consciousness. You can call this direction progress or by some other name.

An accident, a random change, in any delicate mechanism can hardly be expected to improve it. Poking a stick into the machinery of one's watch or one's radio set will seldom make it work better.

The more we know, the better we realize that our knowledge is a little island in the midst of an ocean of ignorance.