Rabbi Oury Cherki
Just what is the soul of man? There have been many attempts to define it. There are some who try to constrict it into the tiny realm of biomolecules, what is called the "animal soul," so that when a person dies his soul also disappears. Some even view it as an illusion, leading to the conclusion that man has no soul even while he is alive. As opposed to these approaches, the religious masters insist that the soul is eternal, and that it is a spark of the Divine which can never be destroyed.
This primal question was debated by the disciples of Aristotle, Alexander of Aphrodisias and Themistius. The first one felt that the soul of man is basically identical with the animal soul but that it has a potential, a "readiness," to become eternal by the study of philosophy if it has merit. The second one felt that the soul is eternal from the beginning but that it has to enhance its perfection. These two approaches were adopted by the Rambam and the Ramban, respectively. Rav Kook put forward an innovative approach, that this describes the difference between the souls of Yisrael and those of the other nations (Olat Re’Iyah volume 2, page 156).
If we look at this matter without any prior opinions, we cannot ignore the fact that there is in mankind a constant tension between two types of identity. On one hand, I am pulled to my natural animal outlook, which is called "dust of the earth" and a "serpent" in the Torah. On the other hand, I encounter within me a personality, a "me" which cannot be reduced to a biological machine, and it constantly thirsts for the metaphysical and for moral values. This can be called "the living soul" or "a part of G-d above." The encounter between these two elements creates the actual man: "a living soul."
This leads almost automatically to the division in the levels of the soul that was described by the masters of Kabbalah: Nefesh (soul), Ruach (air), and Neshamah (spirit), which are described by the sages (Bereishit Rabba 14). The nefesh, which is combined with the body (see the Zohar: "body and soul are one"), is identical to the revealed "me," and it accompanies man from the first moment of his own awareness. The neshamah represents the most noble and ideal dimension of mankind, and it is buried deep within his identity. The ruach represents the changing relationship between the nefesh and the neshamah. This is the least stable element of mankind, where the labors of his life take place. A parallel can be drawn between the triplet nefesh-ruach-neshama and the times: past, present, and future. The nefesh is involved in the past and the neshama is related to the ideal of the future, while the ruach is the present in which man operates.
Who, then, is the man about whom we discuss the nefesh, the ruach, and the neshamah? We cannot allow ourselves to view mankind as nothing more than an assembly of separate parts. We must assume that man has a self-consciousness which precedes these three characteristics. This is what is called: "chayah" – an "animal." It represents the general life, which is the essence of mankind.
Every soul (neshamah) is an expression of the Divine will and serves as part of the general plan of G-d. We can thus say that every soul is related in some way to infinity – and this is called "yechidah" – a unique unit.