Full Idea
I can express the motion of my body through the motion of a point, since its volume is not relevant, but I could not infer from this that if I know nothing except the moving force of a body, that then the body can be conceived as a simple substance.
Clarification
The 'point' is the centre of gravity
Gist of Idea
I can express the motion of my body in a single point, but that doesn't mean it is a simple substance
Source
Immanuel Kant (Critique of Pure Reason [1781], B812/A784)
Book Reference
Kant,Immanuel: 'Critique of Pure Reason', ed/tr. Guyer,P /Wood,A W [CUO 1998], p.666
A Reaction
A nice analogy. The centre of gravity of a body is an abstraction, and people (such as Cartesians) who represent personal identity as being atomic seem to be discussing an abstraction rather than the real thing. My personal self is a bit of a mess.