Graham Harman and Alfred North Whitehead have a lot in common, but they differ in what they say about substance as a metaphysical category. I think Harman overstates this difference. Whitehead suggests “the whole universe consists of elements disclosed in the experiences of subjects” (Process and Reality, p. 166). This multiple disclosure of the One is an ongoing creative process, where the momentary subject (or “superject”) who apprehends the universe’s local appearance becomes a monad, a word Whitehead remarks “expresses [the subject’s] essential unity at the decisive moment, which stands between its birth and its perishing” (PR, p. 88). In this moment of concrescence, “the many become one, and are increased by one.”
Whitehead, then, does recognize the way in which an actual entity withdrawals from its relations and qualities: it does so precisely as a subject. An object’s (or “subject-superject’s,” in Whitehead’s terms) private subsistence apart from the sensual world is fleeting, almost immediately perishing back into the world, but because in this brief moment it enjoys and decides upon the ideal possibilities of its own future, it adds something new to the cosmic process. An object is withdrawn, for Whitehead, because this enjoyment and decision can never be directly caused by any of its relations.
Footnotes2Plato 
What do you think?