Every human being should always be treated as an end and never as a mere instrument.

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.

The greatest problem for the human species, the solution of which nature compels him to seek, is that of attaining a civil society which can administer justice universally.

In all judgements by which we describe anything as beautiful, we allow no one to be of another opinion.

It is the Land of Truth (enchanted name!), surrounded by a wide and stormy ocean, the true home of illusion, where many a fog bank and ice, that soon melts away, tempt us to believe in new lands, while constantly deceiving the adventurous mariner with vain hopes, and involving him in adventures which he can never leave, yet never bring to an end.

Two things fill the mind with ever-increasing wonder and awe, the more often and the more intensely the mind of thought is drawn to them: the starry heavens above me and the moral law within me... Morality is not properly the doctrine of how we may make ourselves happy, but how we may make ourselves worthy of happiness.

The science of mathematics presents the most brilliant example of how pure reason may successfully enlarge its domain without the aid of experience