"Nothing in biology makes sense except in the light of evolution." -- Theodosius Dobzhansky.
"The distinguished American philosopher Daniel Dennett has credited Darwin with the greatest idea ever to occur to a human mind. This was natural selection, the survival of the fittest, of course, and I would include sexual selection as part of the same idea. But Darwin was not only a deep thinker, he was a naturalist of encyclopaedic knowledge and (which by no means necessarily follows) the ability to hold it in his head and deploy it in constructive directions." -- Richard Dawkins.