I want to be thoroughly used up when I die, for the harder I work the more I live. I rejoice in life for its own sake.

The worst sin... is... to be indifferent.

In the arts of life main invents nothing; but in the arts of death he outdoes Nature herself, and produces by chemistry and machinery all the slaughter of plague, pestilence and famine. ... There is nothing in Man's industrial machinery but his greed and sloth: his heart is in his weapons.

My heart, my heart, be whole and free: Love is thine only enemy.

There is, on the whole, nothing on earth intended for innocent people so horrible as a school. To begin with, it is a prison. But in some respects more cruel than a prison. In a prison, for instance, you are not forced to read books written by the warders and the governor. . . .In the prison you are not forced to sit listening to turnkeys discoursing without charm or interest on subjects that they don't understand and don't care about, and therefore incapable of making you understand or care about. In a prison they may torture your body; but they do not torture your brains.

Use your health, even to the point of wearing it out.

Beware of false knowledge; it is more dangerous than ignorance.