When the ordinary thought of a highly cultivated people begins to regard "having children" as a question of pro's and con's, the great turning-point has come. For Nature knows nothing of pro and con. Everywhere, wherever life is actual, reigns an inward organic logic, an "it," a drive, that is utterly independent of waking-being, with its causal linkages, and indeed not even observed by it. The abundant proliferation of primitive peoples is a natural phenomenon, which is not even thought about, still less judged as to its utility or the reverse. When reasons have to be put forward at all in a question of life, life itself has become questionable. At that point begins prudent limitation of the number of births. In the Classical world the practice was deplored by Polybius as the ruin of Greece, and yet even at his date it had long been established in great cities; in subsequent Roman times it became appallingly general. At first explained by the economic misery of the times, very soon it ceased to explain itself at all. And at that point, too, in Buddhist India as in Babylon, in Rome as in our own cities, a man's choice of the woman who is to be, not mother of his children as amongst peasants and primitives, but his own "companion for life," becomes a problem of mentalities.

-Oswald Spengler, The Decline of the West