Quote from : A Posthumous Confession Book

Only a fool can be happy. For happiness consists of two contradictory elements: contentment and pleasure. Enjoy pleasure and you have no contentment; be content and you have no pleasure. For this reason happiness is conceivable only for those who enjoy themselves without thinking that they will always want more and thus be discontented, or for those who are content without thinking that they have no pleasure. Whoever reflects can never be happy, unless he is a fanatic and thus blinded…thus exercising control over his intelligence with his feelings, instead of the other way round