A passionate obsession with the outside world or the private lives of others is an attempt to compensate for a lack of meaning in one's own life

Propaganda ... serves more to justify ourselves than to convince others; and the more reason we have to feel guilty, the more fervent our propaganda.

The Paleolithic hunters who painted the unsurpassed animal murals on the ceiling of the cave at Altamira had only rudimentary tools. Art is older than production for use, and play older than work. Man was shaped less by what he had to do than by what he did in playful moments. It is the child in man that is the source of his uniqueness and creativeness, and the playground is the optimal milieu for the unfolding of his capacities.

It is remarkable by how much a pinch of malice enhances the penetrating power of an idea or an opinion. Our ears, it seems, are wonderfully attuned to sneers and evil reports about our fellow men.

Our credulity is greatest concerning the things we know least about. And since we know least about ourselves, we are ready to believe all that is said about us. Hence the mysterious power of both flattery and calumny.

We are more prone to generalize the bad than the good. We assume that the bad is more potent and contagious.

One word characterizes the most strenuous of the efforts for the advancement of science that I have made perservereingly during fifty-five years; that word is failure