We can judge the heart of a man by his treatment of animals.

The instruction of children should aim gradually to combine knowing and doing. Among all sciences mathematics seems to be the only one of a kind to satisfy this aim most completely.

Do the right thing because it is right.

The busier we are, the more acutely we feel that we live, the more conscious we are of life.

Nature does nothing in vain, and in the use of means to her goals she is not prodigal.

Rules for Happiness: something to do, someone to love, something to hope for.

It is by his activities and not by enjoyment that man feels he is alive. In idleness we not only feel that life is fleeting, but we also feel lifeless.