 Apperception is not only a synthetic process; it is also governed by rules of separation. Apperceptive separation operates only upon the representations already synthesized out of the “associative stock [Assoziationsvorrath]”, but does not necessarily decompose them into their original parts (PP II: 478). Wundt’s notion of apperceptive separation is one of the most philosophically original, consequential, and ambiguous of his theories. He argues that it is usually the case that