He who is cruel to animals becomes hard also in his dealings with men. We can judge the heart of a man by his treatment of animals.

So act that anything you do may become universal law.

In man (as the only rational creature on earth) those natural capacities which are directed to the use of his reason are to be fully developed only in the race, not in the individual.

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

An action is essentially good if the motive of the agent be good, regardless of the consequences.

The enjoyment of power inevitably corrupts the judgment of reason, and perverts its liberty.

Thoughts without content are empty, intuitions without concepts are blind... The understanding can intuit nothing, the senses can think nothing. Only through their union can knowledge arise.