There is only one thing about which I am certain, and this is that there is very little about which one can be certain

We are like people living in a country whose language they know so little that, with all manner of beautiful and profound things to say, they are condemned to the banalities of the conversation manual. Their brain is seething with ideas, and they can only tell you that the umbrella of the gardener's aunt is in the house.

On the earth, satellite of a star speeding through space, living things had arisen under the influence of conditions which were part of the planet's history; and as there had been a beginning of life upon it, so, under the influence of other conditions, there would be an end: man, no more significant than other forms of life, had come not as the climax of creation but as a physical reaction to the environment.

It is not difficult to be unconventional in the eyes of the world when your unconventionality is but the convention of your set.

Perfection has one grave defect: it is apt to be dull.

You will have to learn many tedious things,...which you will forget the moment you have passed your final examination, but in anatomy it is better to have learned and lost than never to have learned at all.

There is no explanation for evil. It must be looked upon as a necessary part of the order of the universe. To ignore it is childish, to bewail it senseless.