Again, you may look upon life as an unprofitable episode, disturbing the blessed calm on non-existence. And, in any case, even though things have gone with you tolerably well, the longer you live the more clearly you will feel that, on the whole, life is a disappointment, nay, a cheat.
[...]
He who lives to see two or three generations is like a man who sits some time in the conjurer's booth at a fair, and witnesses the performance twice or thrice in succession. The tricks were meant to be seen only once; and when they are no longer a novelty and cease to deceive their effect is gone.
[...]
If children were brought into the world by an act of pure reason alone, would the human race continue to exist? Would not a man rather have so much sympathy with the coming generation as to spare it the burden of existence? or at any rate not take it upon himself to impose that burden upon it in cold blood.
I shall be told, I suppose, that my philosophy is comfortless - because I speak the truth; and people prefer to be assured that everything the Lord has made is good. Go to the priests, then, and leave philosophers in peace! At any rate, do not ask us to accommodate our doctrines to the lessons you have been taught. That is what those rascals of sham philosophers will do for you. Ask them for any doctrine you please, and you will get it. Your University professors are bound to preach optimism; and it is an easy and agreeable task to upset their theories.
On the Sufferings of the World, Arthur Schopenhauer