The Simplest Body in the Spinoza’s Physics

In Spinoza’s physics, there is a controversial concept, that is, the simplest body. In order to explicate this concept this paper makes a comparison between Spinoza’s physics with Descartes’, focusing on similarities rather than differences. The main assertions are as follows. First, the simplest body is the perfectly solid body which is Descartes ’ concept in Principles of Philosophy (PP). Second, the constitution of Spinoza’s The Short Treatise on Physics corresponds with the constitution of PP. The latter is arranged from kinetics of solid bodies to a kinetic of fluid bodies, and the former is arranged from the simplest body to the composite body. Third, this order can be understood as concretization. The simplest body or the perfectly solid body is the highest degree of abstraction. Forth, this abstraction is categorized into two kinds of abstraction, abstraction of the exterior and abstraction of the interior. The simplest body is a result of these two kinds of abstraction.