I am Yosef Mengalus, a mage and Philanthropist with an interest in studying the metaphysical. The soul is the core of the human being, and the seat of what makes a person "them". Personality, emotions, ethics, consciousness , etc, are all seated within and controlled by the soul, as well as the life energy that allows the body to function. Through research, I have discovered a way to manipulate the soul to provide for a continously source of energy.
By cutting the link and disconnecting a person from their soul, I can gain access to the energy contained within it. This turns an individual into a container for soul energy, which I can extract at one's convenience in the use of spells. A person in this state is little more than a drone, with no will of their own and whose existence revolves around serving their master. Due to their ease of access and anonymity, and requirement of less energy to maintain, I have decided to use orphans, prisoners, criminals, liberals, etc: the typical dregs of society that produce nothing of value and won't be missed. These people are turned into obedient, productive workers for the state. When they are no longer functional for any reason, due to wear and tear or bodily damage from outside forces, their soul energy can be removed to provide power for a certain spell or ritual.
My philanthropic works have provided my government with a continued source of productive workers. In my mercy and acts of kindness, I have prevented these unwanted individuals from being an unnecessary burden on society and have given value to their meaningless lives. However, this business of immortality due to the disconnection of the soul puzzles me.
If the soul provides life energy to the individual in order for them to function, how can removing it give them immortality?