Give me matter, and I will construct a world out of it!

It is by his activities and not by enjoyment that man feels he is alive. In idleness we not only feel that life is fleeting, but we also feel lifeless.

Natural science physics contains in itself synthetical judgments a priori, as principles. ... Space then is a necessary representation a priori, which serves for the foundation of all external intuitions.

Enlightenment is man's emergence from his self-incurred immaturity.

Reason should investigate its own parameters before declaring its omniscience.

I assert that, in any particular natural science, one encounters genuine scientific substance only to the extent that mathematics is present.

The sceptics, a kind of nomads, despising all settled culture of the land, broke up from time to time all civil society. Fortunately their number was small, and they could not prevent the old settlers from returning to cultivate the ground afresh, though without any fixed plan or agreement.