Criticism alone can sever the root of materialism, fatalism, atheism, free-thinking, fanaticism, and superstition, which can be injurious universally; as well as of idealism and skepticism, which are dangerous chiefly to the Schools, and hardly allow of being handed on to the public.
I freely admit that the remembrance of David Hume was the very thing that many years ago first interrupted my dogmatic slumber and gave a completely different direction to my researches in the field of speculative philosophy.
Every man is to be respected as an absolute end in himself; and it is a crime against the dignity that belongs to him as a human being, to use him as a mere means for some external purpose.
cruelty to animals is contrary to man's duty to himself, because it deadens in him the feeling of sympathy for their sufferings, and thus a natural tendency that is very useful to morality in relation to other human beings is weakened.
Deaths, births, and marriages, considering how much they are separately dependent on the freedom of the human will, should seem to be subject to no law according to which any calculation could be made beforehand of their amount; and yet the yearly registers of these events in great countries prove that they go on with as much conformity to the laws of nature as the oscillations of the weather.
If an offender has committed murder, he must die. In this case, no possible substitute can satisfy justice. For there is no parallel between death and even the most miserable life, so that there is no equality of crime and retribution unless the perpetrator is judicially put to death.
Intuition and concepts constitute... the elements of all our knowledge, so that neither concepts without an intuition in some way corresponding to them, nor intuition without concepts, can yield knowledge.