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.

Notion without intuition is empty, intuition without notion is blind.

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.

Always recognize that human individuals are ends, and do not use them as means to your end.

Two things fill the mind with ever new and increasing admiration and awe, the oftener and more steadily we reflect on them: the starry heavens above and the moral law within.

Even philosophers will praise war as ennobling mankind, forgetting the Greek who said: 'War is bad in that it begets more evil than it kills.'

Why were a few, or a single one, made at all, if only to exist in order to be made eternally miserable, which is infinitely worse than non-existence?