To help us appreciate further what meditation does and how it works, let us examine another model, the concept of the inclinations, the good and evil yetsers. This paradigm, when viewed in tandem with the above, will facilitate a deeper comprehension of the entire psyche, the uniquely human amalgamation of soul, mind and heart.
Rabbi Chaim Vital, in "Gates of Holiness," (a guide to moral development and spiritual enlightenment,) states that the holy Neshomoh (Divine soul of infinite light that emanates from the interaction of the G-dly Ten Sephiroth of Atsiluth), when incarnate, is surrounded by two beings from the Angelic realm. These angelic energies consist of a "good" energy and inclination, the Yetser HaTov –יצר הטוב , and the Yetser HoRo – יצר הרע, the evil inclination.
The nature of these forces can be understood by examining the noun "yetser", from whence its derivatives, Yetser HaTov and Yetser HoRo. To find the true implication of a Hebrew word, we look at the first time it is used in the Torah; its first context gives a clue to its essence.
The word yetser originates from the root יצר, Y-TS-R, a verb meaning, "to create." The first time the verb יצר – YTSR is used is in the creation of man: וייצר את האדם – "and He created man" (Genesis 2:7). This indicates that the yetsers are intrinsic to man's creation, the yetsers' essence bound with man's existence within the physical.
Furthermore, since וייצר – VaYYiTSeR ("and He created") is spelled here with two Yud letters (the only time thus spelled), it is as if the Torah is emphasising that G-d created man with the yetsers because therein lies his purpose of being.
The first time the noun yetser – יצר is used in the Torah is in regard to the evil inclination. G-d says in Genesis (6:5) כי יצר מחשבות לבו רק רע כל היום – "the imagery of his mind's thoughts are only evil the whole day." Yetser here refers to a product, the imagery of the mind. Thus, the Yetser HaTov and Yetser HoRo are by-products, creations, of good and evil.
The mystical texts explain that the dichotomy of the Divine soul within the corporeal necessitates and creates two opposite forces: the two yetsers.
The Yetser HaTov and the Yetser HoRo grow because of the soul's interaction with its physical surroundings. Choices made, and their resultant experiences, give strength to either of the two inclinations and shape their tendencies.
 Sha'arei Qedushoh, Part 3, Gate 2.
 See Part 1, chap 1, p. 31-35.
 A yud in the root is a "weak" letter and normally falls away in the future tense, (the third-person future tense warrants the addition of a yud, as in יאמר,) leavingיצר , meaning "he will create." Here however the original yud of the root has been kept, producing the unusual configuration ofייצר .
 See Berachos 61a.
 The term "evil" is for want of a better word. Evil suggests an absolute absence of good; this is contrary to Jewish thinking which sees רע – ro – as a gross distortion of something that is, at its essence, good energy, or a mixture of 'clean' and 'unclean'. This is reflected in its numerical value, as רע equals the value of the sum of טהור טמא- tohor – the spiritually pure and, tomai - the spiritually unclean. What we will see is that the yetser horo is created through living in this world. It is the inner impulse to survive. When that impulse becomes narcissistic, turned malignantly inwards, it is evil. Interestingly, "evil" is "live" turned backwards! Similarly, רע reversed - ער, means awake, i.e. participating in life.
 Eits Chaim, Gate 50, Chapter 1.