There can be no doubt that all our knowledge begins with experience.

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

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

By a lie, a man... annihilates his dignity as a man.

One who makes himself a worm cannot complain afterwards if people step on him.

Both love of mankind, and respect for their rights are duties; the former however is only a conditional, the latter an unconditional, purely imperative duty, which he must be perfectly certain not to have transgressed who would give himself up to the secret emotions arising from benevolence.

Happiness, though an indefinite concept, is the goal of all rational beings