Nietzsche's break with Schopenhauer rests on precisely this point; it is a matter of knowing whether the will is unitary or multiple.
Gilles DeleuzePhilosophy is not in a state of external reflection on other domains, but in a state of active and internal alliance with them, and it is neither more abstract nor more difficult.
Gilles DeleuzeTo become imperceptible oneself, to have dismantled love in order to become capable of loving. To have dismantled one's self in order finally to be alone and meet the true double at the other end of the line. A clandestine passenger on a motionless voyage. To become like everybody else; but this, precisely, is a becoming only for one who knows how to be nobody, to no longer be anybody. To paint oneself gray on gray.
Gilles Deleuze