The great tragedy of science - the slaying of a beautiful hypothesis by an ugly fact.

That which endures is not one or another association of living forms, but the process of which the cosmos is the product, and of which these are among the transitory expressions.

Next to being right in this world, the best of all things is to be clearly and definitely wrong, because you will come out somewhere. If you go buzzing about between right and wrong, vibrating and fluctuating, you come out nowhere; but if you are absolutely and thoroughly and persistently wrong, you must, some of these days, have the extreme good fortune of knocking your head against a fact, and that sets you all straight again.

Science is simply common sense at its best.

Agnosticism, in fact, is not a creed, but a method, the essence of which lies in the rigorous application of a single principle. ... Positively the principle may be expressed: In matters of the intellect, follow your reason as far as it will take you, without regard to any other consideration. And negatively: In matters of the intellect, do not pretend that conclusions are certain which are not demonstrated or demonstrable.

My reflection, when I first made myself master of the central idea of the 'Origin', was, 'How extremely stupid not to have thought of that!'

It is not who is right, but what is right, that is of importance.