When a thoughtful human being has overcome incentives to vice and is aware of having done his bitter duty, he finds himself in a state that could be called happiness, a state of contentment and peace of mind in which virtue is its own reward.
To be beneficent when we can is a duty; and besides this, there are many minds so sympathetically constituted that, without any other motive of vanity or self-interest, they find a pleasure in spreading joy around them, and can take delight in the satisfaction of others so far as it is their own work. But I maintain that in such a case an action of this kind, however proper, however amiable it may be, has nevertheless no true moral worth, but is on a level with other inclinations. . . . For the maxim lacks the moral import, namely, that such actions be done from duty, not from inclination.
The evil effect of science upon men is principally this, that by far the greatest number of those who wish to display a knowledge of it accomplish no improvement at all of the understanding, but only a perversity of it, not to mention that it serves most of them as a tool of vanity.
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.
We ourselves introduce that order and regularity in the appearance which we entitle "nature". We could never find them in appearances had we not ourselves, by the nature of our own mind, originally set them there.
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.
It is presumed that there exists a great unity in nature, in respect of the adequacy of a single cause to account for many different kinds of consequences.
Upon the solution of this problem, or upon sufficient proof of the impossibility of synthetical knowledge a priori, depends the existence or downfall of metaphysics.
I feel a complete thirst for knowledge and an eager unrest to go further in it as well as satisfaction at every acquisition. There was a time when I believed that this alone could constitute the honor of mankind, and I had contempt for the ignorant rabble who know nothing.