We are enriched not by what we possess, but by what we can do without. - Immanuel Kant

Philosophical knowledge is the knowledge gained by reason from concepts; mathematical knowledge is the knowledge gained by reason from the construction of concepts.

We must not, however, begin with theology. The religion which is founded merely on theology can never contain anything of morality. Hence we derive no other feelings from it but fear on the one hand, and hope of reward on the other, and this produces merely a superstitious cult. Morality, then, must come first and theology follow; and that is religion.

The character of the species, as it is indicated by the experience of all ages and all peoples, is this: that taken collectively (the human race as one whole), it is a multitude of persons, existing successively and side by side, who cannot do without associating peacefully and yet cannot avoid constantly offending one another.