The body, the garment
(Yashar koach to YN for the following translation)
It is know [to mekubalim] that the body of man is not the man himself, because it is called “the flesh of man”, as is written (Iyov 10:11) “Enclothe me in skin and flesh, and cover me with bones and sinews”[…]. Thus, the man is the pnimiyus [inner aspect], but the body is a single garment in which is enclothed the Nefesh Hasichlis [“thinking soul”], which is the man himself for as long as he is in this world. After he passes away he removes this garment from himself and enclothes himself in a refined, clean, spiritual garment, as the verse states (Zecharia 3:4) “remove the filthy garments…I have clad you with clean garments”[…]
Just as a garment for a man’s body is made by an artisan in the form of the limbs of the body, so too [Hashem] makes the body, which is the garment of the nefesh, in the exact form of the nefesh with 248 evarim [limbs] and 365 giddim [sinews] which connect the limbs [just as the nefesh has] and so the limbs and organs of the nefesh perform their actions via the limbs and organs of the body like an axe in the hand of the chopper. The proof of this is that the limbs and organs of the body do not do anything unless the nefesh is within them, the eye which sees and the ear which hears, etc., and when the nefesh leaves the body the [eyes] go dark and all the senses of the limbs cease.
In this way the 365 spiritual giddim of the nefesh are enclothed in the 365 giddim of the body, and draw the bodily nutrition, which is the blood, to the 248 evarim of the body with the inner spiritual nutrtion within it to nourish the 248 evarim of the nefesh. After his passing there is no life-force coming [from the nefesh], and the giddim of the body separate and decay as though the 248 evarim never existed. Thus we see that the man himself is nothing but the Nefesh Hasichlis which is enclothed in the body, which is called its garment in this world.
And know that after Adam Harishon sinned and ate from the Eitz Hada’as Tov v’Ra (tree of knowledge of good and evil) he intermingled his nefesh and his body with good and evil, and this is the zuhama of the nachash (“pollution of the primordial snake”) that [the nachash] put into Chava and Adam, and this evil and zuhama caused illness and disease and death to their nefesh and their body, and this is what is written: “on the day you will eat from it you will die”, death of the nefesh and death of the body.
R’ Chayim Vital, Shaarei Kedusha, Chelek I, part I