My mind seems to have become a kind of machine for grinding general laws out of large collections of facts.

On the ordinary view of each species having been independently created, we gain no scientific explanation.

The very essence of instinct is that it's followed independently of reason.

What a book a devil's chaplain might write on the clumsy, wasteful, blundering, low, and horribly cruel work of nature!

We can allow satellites, planets, suns, universe, nay whole systems of universes, to be governed by laws, but the smallest insect, we wish to be created at once by special act.

A man who dares to waste one hour of time has not discovered the value of life.

It is not the strongest of the species that survives, nor the most intelligent that survives. It is the one that is the most adaptable to change.

An American monkey, after getting drunk on brandy, would never touch it again, and thus is much wiser than most men.

Ignorance more frequently begets confidence than does knowledge: it is those who know little, and not those who know much, who so positively assert that this or that problem will never be solved by science.

The mystery of the beginning of all things is insoluble by us; and I for one must be content to remain an agnostic.

In the long history of humankind (and animal kind, too) those who learned to collaborate and improvise most effectively have prevailed.

A man's friendships are one of the best measures of his worth.

If the misery of the poor be caused not by the laws of nature, but by our institutions, great is our sin.

The highest possible stage in moral culture is when we recognize that we ought to control our thoughts.

I have tried lately to read Shakespeare, and found it so intolerably dull that it nauseated me.

I cannot persuade myself that a beneficent and omnipotent God would have designedly created parasitic wasps with the express intention of their feeding within the living bodies of Caterpillars.

To kill an error is as good a service as, and sometimes even better than, the establishing of a new truth or fact.

A moral being is one who is capable of reflecting on his past actions and their motives - of approving of some and disapproving of others.

A scientific man ought to have no wishes, no affections, - a mere heart of stone.

How paramount the future is to the present when one is surrounded by children.