It is an error to imagine that evolution signifies a constant tendency to increased perfection. That process undoubtedly involves a constant remodelling of the organism in adaptation to new conditions; but it depends on the nature of those conditions whether the directions of the modifications effected shall be upward or

Only one absolute certainty is possible to man, namely that at any given moment the feeling which he has exists.

There is no greater mistake than the hasty conclusion that opinions are worthless because they are badly argued.

If a little knowledge is dangerous, where is the man who has so much as to be out of danger.

Only a scientific people can survive in a scientific future.

The great tragedy of Science – the slaying of a beautiful hypothesis by an ugly fact.

God give me strength to face a fact though it slay me.

Make up your mind to act decidedly and take the consequences. No good is ever done in this world by hesitation.