Next point: by means of speech, tradition, and invention, man has been enabled to extend his biological environment--in other words, that part of the cosmos with which he stands in relation--till it has reached an enormously greater size than that of any other organism. He is learning ever more facts about the celestial bodies, studying stars that are at an inconceivable distance from him. He is able to travel at will to all parts of the globe. He can penetrate by means of tradition to remote periods of the past: as Mr. Wells has forcibly put it, a modern Englishman can know more of the world in the Classical Epoch than could the most learned Greek or Roman. And even when he can no more get into contact with ideas, he can still unravel facts: flint implements help him to the history of man, fossils to that of life, rocks to that of the globe, stars to that of the solar system. In time, as well as in space, his environment enlarges to a size that is for practical purposes infinite, whereas no other organism can penetrate beyond its own memories, or, at most, do more than profit by those of the generation immediately before it. Professor Keyser,[20] in a suggestive article, has characterized this unique attribute of man by calling him “the time-binder.” Speech and reasoning, with all their consequences, have only been rendered possible through another important qualitative change in the human brain, which in its turn has led to other new potentialities of life being realized in man and in man alone--its flexibility.