1 ENTRY “PARS” for The Bloomsbury Companion (update 2022) to Spinoza Dr. Filip Buyse Spinoza argues in both Letter 12 (1663) to his friend L. Meijer, as well as in his Ethics (E1p15s), that the corporeal substance is not divisible and, consequently, is not composed of parts. Nevertheless, he often mentions parts while discussing the corporeal substance, and his friends use the Dutch equivalent for parts (“deeltjes”) in their translations in the Nagelate Schriften (1677). Moreover, he defines a body as a whole of parts, which keep their separateness within this physical individuality, just after E2p13s in his Physical Interlude. However, the Dutch philosopher makes a strict distinction between two ways of conceiving of the corporal substance in 1p15s: the corporeal substance conceived as substance (materia, quatenus substantia) and the corporeal substance conceived modally. He points out that a body is not divisible when conceived of substantially, in both his Letter on the Infinite and in E1p15s. By contrast, the same body is divisible when conceived of modally and is composed of modally distinct parts. (E2p13def) He illustrates this view on the parts/whole relation, using the examples of water and the pendulum clock, in his proto- Ethica, the Short treatise (KV 2.19). The paradigm of the clock was important in Robert Boyle’s Mechanical Philosophy which he introduced in Certain Physiological Essays (1661) and sent in 1661, via H. Oldenburg, to Spinoza. In De nitro (1661), Boyle tried to convince his readers via the so-called Redintegratio experiment that you can decompose and recompose a substance just as pendulum clock. (Buyse 2020) However, the pendulum clock disappears in the corresponding passage of the Ethics (E1p15s). Furthermore, according to Spinoza, the reason why people start to think that the corporeal substance ought to be conceived of as a substance that is composed of parts is because they are deceived by the senses (Ep. 6 & 1p15s) In his Physical Interlude, the Dutch philosopher treats bodies according to their level of complexity, starting with the simplest bodies (corpora simplicissima) which are both parts of bodies and which are part of more complex bodies. Ultimately, all bodies are parts of the unique, infinite, and eternal nature that implies all existing bodies (Ep13s). How these corpora simpliccisima should be understood is still a matter of