It is not the strongest of the species that survives, nor the most intelligent, but the one most responsive to change.
A man who dares to waste one hour of time has not discovered the value of life.
The mystery of the beginning of all things is insoluble by us; and I for one must be content to remain an agnostic.
If I had my life to live over again, I would have made a rule to read some poetry and listen to some music at least once a week.
The highest possible stage in moral culture is when we recognise that we ought to control our thoughts.
The fact of evolution is the backbone of biology, and biology is thus in the peculiar position of being a science founded on an improved theory, is it then a science or faith?
Even in the worm that crawls in the earth there glows a divine spark. When you slaughter a creature, you slaughter God.
An American Monkey after getting drunk on Brandy would never touch it again, and thus is much wiser than most men.
Besides love and sympathy, animals exhibit other qualities connected with the social instincts which in us would be called moral.
In the long history of humankind (and animal kind, too) those who learned to collaborate and improvise most effectively have prevailed.
A scientific man ought to have no wishes, no affections, – a mere heart of stone.
Man tends to increase at a greater rate than his means of subsistence.