ABSTRACT
Man, as time counts in geology and in the history of evolution, is a very recent arrival in his planet. For countless millions of years only very simple animals existed. During other countless millions, new types gradually evolved-fishes, reptiles, birds and, at last, mammals. Man, the species to which we happen to belong, has existed for, at most, a million years, and has possessed his present brain capacity for only about half that time. But recent as is the emergence of man in the history of the universe, and even in the history of life, the emergence of his titanic powers, at once terrifying and splendid, is very much more recent. It is only about six thousand years since man discovered his capacity for distinctively human activities. These began, we may say, with the invention of writing and the organization of government. Since the beginning of recorded history progress has not been steady, but has been a matter of fits and starts. After the Age of the Pyramids, the first really noteworthy advance was in the time of the Greeks, and after them there was no further advance of comparable importance until about
five hundred years ago. During the last five hundred years changes have occurred with continually increasing frequency, and have at last become so swift that an old man can scarcely hope to understand the world in which he finds himself. It seems hardly possible that a state of affairs differing so profoundly from everything that has existed since first there were living organisms, can continue without bringing some kind of dizziness, some calamitous vertigo, that will end the maddening acceleration in which heart and brain become increasingly exhausted. Such fears are not irrational: the state of the world encourages them, and the contrast between the hustling present and the leisurely past brings them to the imagination of the contemplative historian.
