The resistance to a new idea increases by the square of its importance.

One's work is never so bad as it appears on bad days, nor so good as it appears on good days.

What will be the good of the conquest of leisure and health, if no one remembers how to use them?

There can't be a practical reason for believing something that is not true.

Diversity is essential to happiness and in Utopia there is hardly any. This is a defect in all planned social systems.

To be able to concentrate for a considerable time is essential to difficult achievement.

Morally, a philosopher who uses his professional competence for anything except a disinterested search for truth is guilty of a kind of treachery.