Ecclesiaste 3:21 Cabala: Zohar & Reshit Chokhmah

Sitrei Torah The Holy One, blessed be He, alluded to the supernal Wisdom through Abraham and Isaac; Abraham is the Neshamah of Neshamah, (referred to as 'the light of Chayah'). Sarah is the Neshamah, and Lot is the serpent, the spouse of Samael. The holy Ruach is Isaac; the Holy Nefesh is Rivkah. The Evil Inclination is the bestial Nefesh. And concerning this King Solomon said in his wisdom, "Who knows whether the spirit of man goes upwards, and the spirit of the beast goes downwards" (Kohelet 3:21). The bestial Nefesh is the Nefesh that comes from the side of the Evil Inclination.

Let us return to the first subject of this passage, where it is written, "The watchmen that go about the city found me..." (Shir Hashirim 5:7). have guards stationed upon them. As it is written, "I have set watchmen upon your walls, Jerusalem..." (Yeshayah 62:6). And Michael, the High Priest, is the highest of the gate watchmen.

In Tractate Kalah (Bride) its says: Rebbi says “’enflaming yourselves with idols’ (Isaiah 57:5), whoever enflames himself to emit semen in vain is considered to be like an animal. Just like an animal does not calculate its actions, has no knowledge of what can cause it death, and does not have a share in the World to Come, so too is he. About him, Solomon said in his wisdom, ‘Who knows the spirit of man whether it goes upward’ (Ecclesiastes 3:21) this alludes to the souls of the Righteous who do not enflame themselves and emit semen in vain. ‘and the spirit of the beast whether it goes downward to the earth?’ (ibid.), this alludes to the souls of the wicked who enflame themselves and emit semen in vain. And whoever enflames himself deserves death, and whoever arouses himself is a renegade, as it says ‘And what he did was evil in the eyes of Hashem" (Genesis 38:7).”