The man who is happy is fulfilling the purpose of existence

But men love abstract reasoning and neat systematization so much that they think nothing of distorting the truth, closing their eyes and ears to contrary evidence to preserve their logical constructions.

Even if we are occupied with important things and even if we attain honour or fall into misfortune, still let us remember how good it once was here, when we were all together united by a good and kind feeling which made us perhaps better than we are.

There is no explaining anything by reasoning and so it is useless to reason.

... the more I learned, the more conscious did I become of the fact that I was ridiculous. So that for me my years of hard work at the university seem in the end to have existed for the sole purpose of demonstrating and proving to me, the more deeply engrossed I became in my studies, that I was an utterly absurd person

Reason is the slave of passion.

What matters," said the prince at last, "is that you have a child's trusting nature and extraordinary truthfulness. Do you know that a great deal can be forgiven you for that alone?