The atoms are indestructible; vital force is not: atoms have no age; vital force is born, grows old, and dies. Why is an octogenarian older than a youth of twenty, since the atoms of which his body is composed have only belonged to his frame a few months, and since atoms are neither old nor young? The constituent elements of his body when analysed have no age, and what is old in him is solely his vital energy, which is but one of the forms of the general energy of the universe, and which in his case has become exhausted. Life is transmitted by generation, and sustains the body instinctively, and, as it were, unconsciously. It has a beginning and an end. It is an unconscious physical force, which organises and maintains the body of which it is the preserving element. The soul is an intellectual, thinking, immaterial being. The world of ideas in which the soul lives is not the world of matter. It has no age, it does not grow old. It is not changed in a few months like the body; for after months, years, dozens of years, we feel that we have preserved our identity--that our _ego_, ourself, is always ours. On the other hand, if the soul did not exist, and if the faculty of thinking were only a function of the brain, we should no longer be able to say that _we have_ a body, for it would be our body, our brain, _that would have us_. Besides, from time to time our consciousness would change; we should no longer have a feeling of identity, and we should no longer be responsible for the resolutions, secreted by the molecules, which had passed through the brain many months before. The soul is not the vital force; for that is limited and is transmitted by generation, has no consciousness of itself, is born, grows up, declines, and dies. All these states are opposed to those of the soul, which is immaterial, unlimited, not transmissible, conscious. [Sidenote: The soul has no limits.]