The great struggle between the determinist and the indeterminist, between the opponent and the sustainer of the freedom of the will, has ended to-day, after more than two thousand years, completely in favor of the determinist. The human will has no more freedom than that of the higher animals, from which it differs only in degree, not in kind. In the last century the dogma of liberty was fought with general philosophic and cosmological arguments. The nineteenth century has given us very different weapons for its definitive destruction--the powerful weapons which we find in the arsenal of comparative physiology and evolution. We now know that each act of the will is as fatally determined by the organization of the individual and as dependent on the momentary condition of his environment as every other psychic activity. The character of the inclination was determined long ago by _heredity_ from parents and ancestors; the determination to each particular act is an instance of _adaptation_ to the circumstances of the moment wherein the strongest motive prevails, according to the laws which govern the statics of emotion. Ontogeny teaches us to understand the evolution of the will in the individual child. Phylogeny reveals to us the historical development of the will within the ranks of our vertebrate ancestors. CHAPTER VIII THE EMBRYOLOGY OF THE SOUL Importance of Ontogeny to Psychology--Development of the Child-Soul--Commencement of Existence of the Individual Soul--The Storing of the Soul--Mythology of the Origin of the Soul--Physiology of the Origin of the Soul--Elementary Processes in Conception--Coalescence of the Ovum and the Spermatozoon--Cell-Love--Heredity of the Soul from Parents and Ancestors--Its Physiological Nature as the Mechanics of the Protoplasm--Blending of Souls (Psychic Amphigony)--Reversion, Psychological Atavism--The Biogenetic Law in Psychology--Palingenetic Repetition and Cenogenetic Modification--Embryonic and Post-Embryonic Psychogeny The human soul--whatever we may hold as to its nature--undergoes a continual development throughout the life of the individual. This ontogenetic fact is of fundamental importance in our monistic psychology, though the "professional" psychologists pay little or no attention to it. Since the embryology of the individual is, on Baer's principle--and in accordance with the universal belief of modern biologists--the "true torch-bearer for all research into the organic body," it will afford us a reliable light on the momentous problems of its psychic activity.