Samach Vav Part 218:

Samach Vav p. 177-178: The soul's great descent -- from the inner (core) containers of Atzilus (unlike angels rooted in the outer containers) -- is not for its own sake but to refine the animal soul. This explains the amount of years designated to a person to live in a body in this world This explains the amount of time a person is given to live in a body in this world: The divine soul itself is eternal, beyond time. But since the soul manifests in a body and animal soul, rooted in the shattered containers that need refinement, it is allocated a certain number of days ( "days have been formed"), corresponding to the specific sparks the soul needs to refine. When no sparks are left to be refined, the lifespan of the animal soul ends, and the sparks are encompassed in, and elevate, the divine soul. This is the meaning of the verse "human and animal You, Hashem, redeem": When the divine soul (adam, rooted in ma"h) refines the animal soul (beheima, rooted in ba"n), it joins them together and brings divine redemption. This is the work of the divine soul during the six weekdays to refine the animal soul.