Probably no invention came more easily to man than heaven.

It is a sure evidence of a good book if it pleases us more and more as we grow older.

Man…who lives in three places – in the past, in the present, and in the future – can be unhappy if one of these three is worthless. Religion has even added a fourth – eternity.

If it were true what in the end would be gained? Nothing but another truth. Is this such a mighty advantage? We have enough old truths still to digest, and even these we would be quite unable to endure if we did not sometimes flavor them with lies.

Just as we outgrow a pair of trousers, we outgrow acquaintances, libraries, principles, etc., at times before they're worn out and times - and this is the worst of all - before we have new ones.

If we make a couple of discoveries here and there we need not believe things will go on like this for ever. Just as we hit water when we dig in the earth, so we discover the incomprehensible sooner or later.

A schoolteacher or professor cannot educate individuals, he educates only species.