The question about the whence and whither of the drift of our cosmic weather is an old one and cannot be lightly brushed aside. It is both a forced and a momentous issue. It is a forced issue, because we cannot help taking an attitude towards it, whether we make it explicit to ourselves or not. It is momentous, because such an attitude is a serious index of our deepest practical faith as regards the value of life, and cannot help determining our conduct. There have been three distinct types of theory in the past as regards this drift—Mechanism, Finalism, and Vitalism.