The only objects of practical reason are therefore those of good and evil. For by the former is meant an object necessarily desired according to a principle of reason; by the latter one necessarily shunned, also according to a principle of reason.

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.

Act in such a way that you treat humanity, whether in your own person or in the person of any other, never merely as a means to an end, but always at the same time as an end.

Prudence reproaches; conscience accuses.

Fallacious and misleading arguments are most easily detected if set out in correct syllogistic form.

This spirit of freedom is expanding even where it must struggle against the external obstacles of governments that misunderstand their own function. Such governments are illuminated by the example that the existence of freedom need not give cause for the least concern regarding public order and harmony in the commonwealth. If only they refrain from inventing artifices to keep themselves in it, men will gradually raise themselves from barbarism.

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.