Every Jew has two souls: a good soul and an evil soul. The good soul enters the evil soul, and both of them dwell within the body and its limbs.

A person has a good soul and an evil soul:

When man sinned through the tree of the knowledge of good and evil, he caused this mix [of good and evil] in all of the worlds [levels of existence]. There is nothing that does not contain a mixture of good and evil…. It turns out that even in a person’s soul this is the case, for he is hewn from the four spiritual elements from which all elevated beings were made, the four letters of the divine name…. This is man’s essential soul, from the side of goodness. But “God made this [good] corresponding to that [evil]” (Ecclesiastes 7:14). This [corresponding evil soul] is called adam beliya’al (the wicked man), and is composed of the four major types of destructiveness, the four types of appearance of leprosy, and, likewise, the four evil elements. From there the evil soul is drawn toward man and is referred to as the yetzer hara (evil inclination). When this soul overcomes a person’s good soul, harm, plagues, and sicknesses of the soul come upon him. If it overcomes [his good soul] even more it will kill him.

Further reading: For more on the body-soul connection and healing the soul, see p. 119; A Concise Guide to the Sages, p. 400.

The good soul is “clothed” in the evil soul, and both of them are “clothed” in the body’s limbs and sinews:

The pure soul, which is the “fruit” is made up of 613 limbs and sinews which are “clothed” within 613 corresponding limbs and sinews of the impure soul. This impure soul is called the “husk of the fruit.” Both souls, together, are clothed in the 613 physical limbs and sinews of the body. It turns out that the limbs of the pure soul are within those of the evil soul, and the limbs of the evil soul are within the limbs of the body. (Rav Ĥayyim Vital, Sha’arei Kedusha 1:1)

Every Jew has two souls, one, called the animal soul, stemming from negative spiritual sources – referred to in kabbalistic literature as the kelipot (husks) and sitra ahra (the “other side“) – and a second soul which is referred to as the divine soul. These two souls battle each other, each trying to gain control of the body, which can be likened to a small city that a powerful king is trying to capture. Victory, for the divine soul, means that the body is totally negated and subjugated to the divine soul. One must remember that the negative soul was also created by God, and He gave it the mandate to challenge and fight the divine soul. It is, therefore, happy when the divine soul overcomes it.

The second, higher soul in a Jew is a fragment of the Most High:

The second soul in a Jew is a fragment of the Most High …Although there are a myriad different levels of the soul, one above the other endlessly…nevertheless, the root of all aspects of the soul in its entirety, from the highest of all levels to the lowest level, which is clothed in the body of the simplest and least-refined person, is drawn from the divine mind, which constitutes supernal wisdom, so to speak.

The structure of the Godly soul:

And so, every aspect and level of these three [components of the soul], nefesh, ruah, and neshama, is comprised of ten aspects, corresponding to the ten supernal sefirot from which they emanated, namely: hokhma, bina, and da’at, as well as the [sefirot known as] “the seven days of construction”: hesed, gevura, tiferet [netzah, hod, yesod, and malkhut]. The [ten qualities of the] human soul are also divided into two categories: the intellectual and emotive attributes…. Furthermore, each divine soul has three “garments,” namely: thought, speech, and action, [aspects of] of the 613 mitzvot of the Torah.

The structure of the soul from the “other side”:

And so, God made this correspond to that. For just as the divine soul [of a person] is comprised of ten holy sefirot and is clothed in three holy garments, this is also [the case with] the soul originating from the sitra ahra of kelipat noga and which is infused in the [person’s] blood. It too is comprised of ten crowns of impurity, which are [divided into] seven evil character traits, stemming from the four base elements mentioned previously, as well as the intellect engendering them, which is comprised of three components: hokhma (wisdom), bina (understanding), and da’at (knowledge). These are the source of the character traits…. When a person thinks or speaks about these [ten impure faculties], or acts on them, then the thought of his mind, the speech of his mouth, and the force of action in his hands and other limbs are referred to as “garments of impurity.”

The battle of the two souls over control of the body:

It is analogous to two kings waging war over a city. Each wants to conquer it and rule over it, which means making the inhabitants follow his will, so that they obey anything he decrees upon them. So too, the two souls, the divine soul and the vital, animalistic soul from the kelipa, battle each other over the body and all its limbs. The divine soul seeks and desires to be its sole ruler, so that all the limbs will be subject to its discipline. [They will then become] a totally subjugated platform for the [divine soul], expressing its ten qualities and three garments, mentioned previously, until they are all clothed in the limbs of the body, such that the body will be infused exclusively with them and nothing foreign will mingle with them, Heaven forbid …. However, the animalistic soul from the kelipa desires the exact opposite, for the [ultimate] good of the person, so that he overcomes it and defeats it. (Rabbi Shneur Zalman of Liadi, Tanya, Likutei Amarim 2–9)

Further reading: For more on the meanings of the terms nefesh, ruah, and neshama, see p. 219.