Life is too short to occupy oneself with the slaying of the slain more than once.

I really see no harm which can come of giving our children a little knowledge of physiology. ... The instruction must be real, based upon observation, eked out by good explanatory diagrams and models, and conveyed by a teacher whose own knowledge has been acquired by a study of the facts; and not the mere catechismal parrot-work which too often usurps the place of elementary teaching.

I have always been, am, and propose to remain a mere scholar. All that I have ever proposed to myself is to say, this and this I have learned; thus and thus have I learned it; go thou and learn better; but do not thrust on my shoulders the responsibility for your own laziness if you elect to take, on my authority, conclusions the value of which you ought to have tested for yourself.

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

A man's worst difficulties begin when he is able to do as he likes.

There is far too much of the feeding-bottle in education and young people ought to be supplied with good intellectual food and then left to help themselves.

No one can help another very much in these crises of life; but love and sympathy count for something.