When we turn from the genetic study of the soul to the great question of its immortality, we come to that highest point of superstition which is regarded as the impregnable citadel of all mystical and dualistic notions. For in this crucial question, more than in any other problem, philosophic thought is complicated by the selfish interest of the human personality, who is determined to have a guarantee of his existence beyond the grave at any price. This “higher necessity of feeling” is so powerful that it sweeps aside all the logical arguments of critical reason. Consciously or unconsciously, most men are influenced in all their general views, and, therefore, in their theory of life, by the dogma of personal immortality; and to this theoretical error must be added practical consequences of the most far-reaching character. It is our task, therefore, to submit every aspect of this important dogma to a critical examination, and to prove its untenability in the light of the empirical data of modern biology.