 On a “deeper level,” as Mendelssohn puts it, he also takes issue with Spinoza for failing to account for what Mendelssohn deems the “formal” aspects of both corporeal and spiritual worlds. Thus, Spinoza’s conception of extension in terms of impenetrability may explain “the essence of matter,” but it leaves unexplained, Mendelssohn contends, the particular organization and movement of bodies. What is unclear to Mendelssohn is how parts can be in motion if the whole upon which they completely depend (Spinoza’s substance) is not in motion. Similarly, he wants to know how, on the basis of Spinoza’s account of the supposedly underlying attribute of extension, those parts come to have the particular form and organization of motions and forces that they have, that is to say, as organic, self-regulating entities. “Where can the origin of this [motion and form] be found?” he asks. “Not in the whole, since the whole has no movement. The sum [Sämmtliche] of all bodies, untied into a single substance, cannot change place and has neither organization nor figure…. Whence the form in the parts, if the whole provides no source for this?” (Gesammelte Schriften, 3/2, p. 108).