Theodosius Dobzhansky

It is the business of science to measure and describe, not to praise or blame.

The first half of the 20th century will be remembered as the time when the basic postulates of the modern theory of evolution were established.

Nature's stern discipline brings to our consciousness that mankind does not conquer nature, but is conquered by it.

The moral sense enables one to perceive wickedness and to demand justice.

Evolution is not progress, but change.

In the last analysis, we must admit that no defining criterion of the species is altogether satisfactory.

The mechanism of natural selection is the most creative of all known causes.

Man's destiny is to know, if he can, the riddles of the universe and control his own fate.

The world has arisen in some way or another. How it originated is the great question, and Darwin's theory, like all other attempts to explain the origin of life, is thus far unsatisfying.

Biology, as a science of life, is a peculiarly human science.

The idea of evolution is older than Darwin, but Darwin put it on a firm foundation.

We are dealing with a process which is essentially creative.

The struggle for existence is a consequence of the tendency to increase.

Human evolution has been a tragedy in many ways, but it has also been a triumph.

The gene is the unit of heredity.

Adaptation is the criterion of fitness.

Evolution is the greatest single scientific discovery of the 19th century.

The harmony of nature is a harmony of contradictions.

Science and religion deal with different aspects of reality.

The species is the only distinct subdivision of the uninterrupted series of organisms.