Sterēsis

The third principle of change

For Aristotle, change requires three things: a substrate, a form gained, and the sterēsis or privation — the lack of that form which the substrate did not yet have. The unmusical becomes musical: matter persists, the form of music is acquired, and the prior privation is left behind. Privation is not mere nothing; it is a determinate absence, the not-yet that makes becoming possible.