Enlightenment is man's emergence from his self-imposed immaturity...No thing is required for this enlightenment.. .except freedom; and the freedom in question is the least harmful of all, namely, the freedom to use reason publicly in all matters.

Innocence is indeed a glorious thing; but, unfortunately, it does not keep very well and is easily led astray.

Only the descent into the hell of self-knowledge can pave the way to godliness.

The greatest human quest is to know what one must do in order to become a human being.

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.

The ultimate destiny of the human race is the greatest moral perfection, provided that it is achieved through human freedom, whereby alone man is capable of the greatest happiness.

If justice perishes, human life on Earth has lost its meaning.