“We may get to know the world however we choose, it will always keep a day and night aspect.”

“We must always change, renew, rejuvenate ourselves; otherwise, we harden.”

“We know accurately only when we know little; doubt grows with knowledge.”

“The greatest thing in this world is not so much where we stand as in what direction we are moving.”

“Difficulties increase the nearer we get to the goal.”

“Knowing is not enough; we must apply. Willing is not enough; we must do.”

“Is it not enough that we cannot make one another happy, must we also rob one another of the pleasures that any heart may permit itself now and then? And name me a person who in a bad mood will be decent enough to hide it, to bear it alone, without destroying the joy around him. Is it not rather an inner dissatisfaction with our own unworthiness, a dislike of ourselves that is always associated with envy aggravated by foolish conceit? We see people happy and not made happy by us, and that is unbearable.”