If there are no soulless bodies, there are also no bodiless souls; the soul is always joined with an aggregate of subordinate monads, though not always with the same ones. Single monads are constantly passing into its body, or into its service, while others are passing out; it is involved in a continuous process of bodily transformation. Usually the change goes on slowly and with a constant replacement of the parts thrown off. If it takes place quickly men call it birth or death. Actual death there is as little as there is an actual genesis; not the soul only, but every living thing is imperishable. Death is decrease and involution, birth increase and evolution. The dying creature loses only a portion of its bodily machine and so returns to the slumberous or germinal condition of "involution", in which it existed before birth, and from which it was aroused through conception to development. Pre-existence as well as post-existence must be conceded both to animals and to men. Leuwenhoek's discovery of the spermatozoa furnished a welcome confirmation for this doctrine, that all individuals have existed since the beginning of the world, at least as preformed germs. The immortality of man, conformably to his superior dignity, differs from the continued existence of all monads, in that after his death he retains memory and the consciousness of his moral personality. %3. Man: Cognition and Volition.% In reason man possesses reflection or self-consciousness as well as the knowledge of God, of the universal, and of the eternal truths or _a priori_ knowledge, while the animal is limited in its perception to experience, and in its reasoning to the connection of perceptions in accordance with memory. Man differs from higher beings in that the majority of his ideas are confused. Under confused ideas Leibnitz includes both sense-perceptions--anyone who has distinct ideas alone, as God, has no sense-perceptions--and the feelings which mediate between the former and the perfectly distinct ideas of rational thought. The delight of music depends, in his opinion, on an unconscious numbering and measuring of the harmonic and rhythmic relations of tones, aesthetic enjoyment of the beautiful in general, and even sensuous pleasure, on the confused perception of a perfection, order, or harmony. The application of the _lex continui_ to the inner life has a very wide range. The principal results are: (1) the mind always thinks; (2) every present idea postulates a previous one from which it has arisen; (3) sensation and thought differ only in degree; (4) in the order of time, the ideas of sense precede those of reason. We are never wholly without ideas, only we are often not conscious of them. If thought ceased in deep sleep, we could have no ideas on awakening, since every representation proceeds from a preceding one, even though it be unconscious.