I shall never forget my mother, for it was she who planted and nurtured the first seeds of good within me. She opened my heart to the lasting impressions of nature; she awakened my understanding and extended my horizon and her percepts exerted an everlasting influence upon the course of my life.

The business of philosophy is not to give rules, but to analyze the private judgments of common reason.

The only thing permanent is change.

I am myself by inclination an investigator.

[Aristotle formal logic thus far (1787)] has not been able to advance a single step, and hence is to all appearances closed and completed.

Even the song of birds, which we can bring under no musical rule, seems to have more freedom, and therefore more for taste, than a song of a human being which is produced in accordance with all the rules of music; for we very much sooner weary of the latter, if it is repeated often and at length. Here, however, we probably confuse our participation in the mirth of a little creature that we love, with the beauty of its song; for if this were exactly imitated by man (as sometimes the notes of the nightingale are) it would seem to our ear quite devoid of taste.

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.