Reason deserves to be called a prophet; for in showing us the consequence and effect of our actions in the present, does it not tell us what the future will be?
Every woman while she would be ready to die of shame if surprised in the act of generation, nonetheless carries her pregnancy without a trace of shame and indeed with a kind of pride. The reason is that pregnancy is in a certain sense a cancellation of the guilt incurred by coitus; thus coitus bears all the shame and disgrace of the affair, while pregnancy, which is so intimately associated with it, stays pure and innocent and is indeed to some extent sacred.
We can come to look upon the deaths of our enemies with as much regret as we feel for those of our friends, namely, when we miss their existence as witnesses to our success.
There is no absurdity so palpable but that it may be firmly planted in the human head if you only begin to inculcate it before the age of five, by constantly repeating it with an air of great solemnity.
There is only one inborn erroneous notion ... that we exist in order to be happy ... So long as we persist in this inborn error ... the world seems to us full of contradictions. For at every step, in great things and small, we are bound to experience that the world and life are certainly not arranged for the purpose of maintaining a happy existence ... hence the countenances of almost all elderly persons wear the expression of ... disappointment.
Of all the intellectual faculties, judgment is the last to mature. A child under the age of fifteen should confine its attention either to subjects like mathematics, in which errors of judgment are impossible, or to subjects in which they are not very dangerous, like languages, natural science, history, etc.
When a new truth enters the world, the first stage of reaction to it is ridicule, the second stage is violent opposition, and in the third stage, that truth comes to be regarded as self-evident.