Things which we see are not by themselves what we see ... It remains completely unknown to us what the objects may be by themselves and apart from the receptivity of our senses. We know nothing but our manner of perceiving them.

The function of the true state is to impose the minimum restrictions and safeguard the maximum liberties of the people, and it never regards the person as a thing.

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.

All human knowledge begins with intuitions, proceeds from thence to concepts, and ends with ideas.

Men will not understand ... that when they fulfil their duties to men, they fulfil thereby God's commandments; that they are consequently always in the service of God, as long as their actions are moral, and that it is absolutely impossible to serve God otherwise.

Animals... are there merely as a means to an end. That end is man.

In the mere concept of one thing it cannot be found any character of its existence.