An action, to have moral worth, must be done from duty.

[A ruler is merely] the trustee of the rights of other men and he must always stand in dread of having in some way violated these rights.

But a lie is a lie, and in itself intrinsically evil, whether it be told with good or bad intents.

Act in such a way that you will be worthy of being happy.

Space and time are the framework within which the mind is constrained to construct its experience of reality.

Procrastination is hardly more evil than grasping impatience.

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.