Answer: We all depend on one another in the spiritual world and are connected into one system, but each of us also carries his own unique element that no one else has. It is called after him, and it is his personal investment in the general system.
He must manage the whole system from the root of his soul, invest in it, and assist it. His investment in the system, which is what he needs to put into it together with all the other souls, is called his soul. This is the reason that everyone is very important. On the one hand, everyone has one single soul, and on the other hand, everyone has his own personal soul.
There is, for example, a Reshimo (Reminiscence) in me called the point in the heart that I must fulfill in order to participate properly in the system of man with all of the other souls. It is actually my participation in it that is called my self. Each of us must fulfill that.
All of the billions of parts of the general soul are inside of me, but the main ones are Abraham, Isaac, Jacob, Moses, Aaron, Joseph, and David. They are the ten main Sefirot of the soul, and all of its other parts are dressed on them, like clusters.
By completing his system, Aaron detaches himself, retreats and joins his forefathers. Now his children continue his spiritual work.
From KabTV’s “Secrets of the Eternal Book” 7/1/15