In general, reality is comprised of two realms: a physical one and spiritual one 1. The physical realm itself is comprised of the things that we can experience with our senses 2, be they the more astronomical sorts of things like the stars and planets, or the more terrestrial ones like the earth, seas, and sky, and all the other things that we can sense.
The spiritual realm is comprised of immaterial things that we can’t experience with our senses. They’re either souls which are the purely spiritual phenomena that enter into, are circumscribed by and are deeply connected to bodies so as to affect them in various ways and at different stages 3. Or they’re transcendent phenomena that never enter into physical bodies like the “forces” 4 and angels 5. The transcendent phenomena exist on different levels, they each have unique natures, and they’re so highly variable that each would seem to be in a class of its own, but they’re all of one sort.
There’s one specific entity, though, that’s a cross between the physical and spiritual in that it can’t be detected by the senses and isn’t bound by the constraints and laws of physicality, and yet it’s very different from angels and forces (despite some similarities). These entities are known as “demons” 6. And they, too, have specific inborn attributes and make-ups, and are also so highly variable that each would seem to be in a class of its own, but are likewise all of one sort.
It’s important to know that only humans consist of the two opposite components of an exalted soul and a lowly body. For while animals have “souls”, those souls aren’t actually spiritual phenomena — even though they’re the most spiritual of material phenomena. And while the same sort “soul” is in humans as well given that we too are mortal beings, we nonetheless also have immortal souls 7 which is an utterly unique entity that’s completely different than a body and incomparable to it, and which comes to us from and is connected to G-d for the reasons we explained above 8. Notes:
1. See Ma’amar HaIkkurim, “B’Ruchniyim”, and Da’at Tevunot 78.
2. Or with devices that expand on them, regardless of how vast or minute, blunt or subtle they may be.
3. The idea that “souls … affect (bodies) in various ways and at different stages” refers to the relationship between bodies and souls in life, in the afterlife, in the resurrection of the dead, and in the world to come.
4. They’re termed “the roots of (all) created phenomena” in 4:6:13 below and are referred to as the Sephirot by the Kabbalists. See Ma’amar HaChochma, “HaSephirot” and elsewhere about them.
5. See 4:6:13 below as well as Pitchei Chochma v’Da’at 108-109, Klallei Pitchei Chochma v’Da’at 5, Da’at Tevunot 116, 118, 126, 160, Derech Eitz Chaim p. 137, Messilat Yesharim Ch. 6, Adir Bamarom pp. 260, 195.
6. As demons are the most foreign to us of all of the above, they call for explanation. For one thing, it’s pointed out in the Talmud that demons are all around us all the time. They’re more numerous than we, and we’d in fact be thunderstruck and undone if we were actually able to see them (Berachot 6A). So they’re obviously a force to be reckoned with. For an exposition about them see Chagiga 16a, Yevamot 122a, Zohar 3:76b, etc. Also see Deuteronomy 32:17 and Psalms 106:37 for Biblical references to them.
Rambam denies their existence in his commentary to Avodah Zarah 4:7 and in Mishne Torah, Avodat Kochavim 11:6, but the Gaon of Vilna excoriates him for that opinion (Yoreh Deah 179:13). See Ramchal’s Iggerot 50 and Derech Eitz Chaim p. 142. Also see Eitz Chaim 50:8 for the Ari’s understanding of them.
7. As it’s said, “And G-d the L-rd formed man out of the dust of the ground and He breathed into his nostrils the soul of life, and man became a living soul.” (Genesis 2:7).
The type of soul that both animals and humans have is known as the Nephesh, while the one that’s unique to humans is known as the Neshama. See 3:1:1-6 below on the different parts of the human soul.
See Rambam’s Sh’mone Perakim, Ch. 1 as well as Ramchal’s Da’at Tevunot 24 and Adir Bamarom pp. 47, 275.
8. In short, only human beings are comprised of the two components of reality itself, both physicality and spirituality, at one and the same time. The forces, angels, and the like are spiritual but not material, and animals are physical but not spiritual (though they have something akin to a soul), and “demons” which seem to be a combination of the two aren’t really so (since they’re not physical, yet they’re also not angelic).
That’s why we humans are referred to as microcosms of the universe (see Tanchuma, Pekudei 3), given that only we are comprised of those two components. Ramchal apparently makes this point to underscore his ongoing idea about our unique situation in the universe.
Rabbi Yaakov Feldman has translated and commented upon “The Gates of Repentance”, “The Path of the Just”, and “The Duties of the Heart” (Jason Aronson Publishers). His works are available in bookstores and in various locations on the Web.