HAVING brought into relief, by the preceding summary, the entire doctrine of successive lives and of re-incarnations, we must now meet some objections which will have been provoked by these propositions, and reply to them in a way which has the advantage of still more distinctly explaining our ideas on several points. First objection. It will be said: The existence of an immortal soul in man forms the basis of all this reasoning. Now, the fact of the existence of an immortal soul is not demonstrated in the course of this work, and, besides, it could not be demonstrated. The following is our reply to this first objection. We are composed of two elements, or of two substances; one which thinks--the soul, or the immaterial substance; the other, which does not think--the body, or the material substance. This truth is self-evident. Thought is a fact, certain in itself; and it is another fact, equally certain, that my arms, my nails or beard, do not think. Here, then, is the proof of the immortality of the soul, or thinking principle. Matter does not perish; observation and science prove that material bodies are never annihilated, that they merely change their condition, their form, and their place; but are always to be found somewhere intact as to their substance. Our bodies decompose, and are dissolved, but the matter of which they were formed is never destroyed, it is dispersed in the air, the fire, and the water, in which it produces new material combinations, but it is not destroyed for all that. Now, if matter does not perish, but only becomes transformed, all the more certainly must the soul be indestructible and imperishable. Like matter, it must be transformed, without being destroyed. Descartes has said, _I think, therefore I am_. This reasoning, so much admired in the schools, has always appeared to us rather weak. To give force to the syllogism, he should have said, _I think, therefore I am immortal_. My soul is immortal, because it exists, and it does exist since I think. Thus the fact of the immortality of the spiritual principle which we bear within us is self-evident, and we do not need any of the demonstrations which abound in philosophical works, and have been put forth from antiquity until our own time; we need no _Treatises on the Soul_ to establish its existence. The difficulty does not consist in proving that a spiritual principle exists within us, that is to say, a principle which resists death, because, in order to contest the existence of this principle, it would be necessary to contest thought. The real problem is to find out whether this spiritual and immortal principle which we bear within us, is to live again, after our death, in ourselves or in others. The question is, whether the immortal soul will be born again in the same individual, physically transformed, in the same person, in the _ego_, or whether it will pass into the possession of a being strange to that person.