My Answer: “Starting from zero” means rejecting our old outlook on things. When a new step begins, that means the previous step has exhausted itself.
Just as each new generation must grow in its own way and avoid pressure from the previous generation, each of the 125 steps of spiritual advancement starts from our material world. As we know, Nukvah (Malchut of the World of Atzilut) becomes a virgin again every day and everything returns to zero so that a new copulation can begin.
Our contact with the Creator does not contain even a single detail of our past state; each time, a new soul is born. This is what we call a “life cycle” (reincarnation). Our previous state matters only insofar as it prepares us for a new level. What happened to us in the past is already gone. We can, and must start all over again! Each new state is a new set of ten Sefirot.
This renovation is necessary to qualitatively, rather than quantitatively, attain the Creator by using new aspects of our egoism and rising above it. This approach is very different from simply erasing our past because it was bad or unpleasant to think about. The same applies to this world. When someone starts a new business and it loses money, they have to shut it down and start again with something new. We cannot achieve anything if we do not consistently and completely renew our state of being.
It is written: “Let every day be a new day.” It is in our nature to continue with things as they are, to continue following the inertia of the past. Let’s learn from our downfalls. When Light is replaced with darkness and is then restored again, each new state is different and does not resemble its predecessors.