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

Physicians think they are doing something for you by labeling what you have as a disease

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.

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

If you punish a child for being naughty, and reward him for being good, he will do right merely for the sake of the reward; and when he goes out into the world and finds that goodness is not always rewarded, nor wickedness always punished, he will grow into a man who only thinks about how he may get on in the world, and does right or wrong according as he finds advantage to himself.

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

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.