If we conceive life as the sum total of all the forces that resist death and death in its essence as the queller of life, it is to biology, not to theology or philosophy, that we must look for our most authoritative and normative ideas of both life and death. We must examine not only the now very copious data that this science already supplies but also the instrument that defines, delivers, and interprets them, namely, the mind, so that psychology must henceforth have a place here second only to biology in formulating conclusions. Now, psychology teaches not only that there are certain determining tendencies that always, in part at least below the threshold of consciousness, direct the course of thought, slowly build up centers of apperception and interest, and that must always be reckoned with sooner or later not only in the treatment of any subject in which their action is involved but also when almost any scientific laws of nature are formulated, but also that, quite apart from their primary significance for the field in which they arose, they have a secondary anagogic value in other fields, in which they become symbols, often of great efficacy. Only the lower alchemists sought to evolve gold from baser metals and this quest we now know was always and everywhere really subordinate to the effort to evolve the _summum bonum_ in human life. So the modern sciences that deal with life and death, health and disease, are really directed far more than they know, even in those researches upon the lower forms of life and most abnormal processes, by the deeper, determining motivation to know better and to influence more the conditions of human life. Thus a truer and larger self-knowledge for man is, in this sense, their ultimate goal.