To be is to do.

That Logic has advanced in this sure course, even from the earliest times, is apparent from the fact that, since Aristotle, it has been unable to advance a step, and thus to all appearance has reached its completion.

Always recognize that human individuals are ends, and do not use them as means to your end.

It is not necessary that whilst I live I live happily; but it is necessary that so long as I live I should live honourably.

Morality is not the doctrine of how we may make ourselves happy, but how we may make ourselves worthy of happiness.

Live your life as though your every act were to become a universal law.