Gassendian bodies are composites of atoms “woven together” with a certain texture. The notion of texture is central to Gassendi's atomism. In theory he relies heavily on the claim that the qualities and behavior of macroscopic bodies derive from the size, shape, and local motion of tiny particles, but in practice Gassendi almost always appeals to the notion of texture in providing explanations of particular bodily phenomena. This is one of the reasons his explanations are almost always qualitative rather than quantitative. Indeed, even in the one case where he provides a relatively detailed quantitative description – the proportion by which bodies in free fall accelerate – Gassendi makes clear that it needs to be grounded in an account of the textures of the relevant bodies. His concern with the new science of motion is above all to explain the underlying causes of motion, causes that must be described in corpuscularian, textural terms.

The program outlined in the initial books of the Syntagma suggests that texture is not something over and above the arrangement of atoms in space. However, it is unclear how we could derive anything that does all the explanatory work Gassendi needs textures to do from patterns of atoms moving in space. This chapter will examine both Gassendi's general account of texture and his account of the underlying causes of the motion of composite bodies. Treating these two issues together has a number of benefits.