  The problem arises in two forms, which, to borrow James Hill’s terminology (Hill 2004), may be called the limited and the foundational problems. The limited problem, arising for those who take corpuscles to be genuine atoms, that is, to be indivisible, is the problem of explaining how those indivisible corpuscles cohere with one another. This is the problem one finds in Newton’s writings. Although Rule 3 of the Principia allows the possibility that the least parts of matter could turn out to be divisible, his atomist sympathies are evident throughout his writings. He speculates in Query 31 that in all probability, bodies are made up of hard particles that only God could divide, and in the body of the Opticks (Book II, Part III, Proposition VII) he suggests that more powerful microscopes might permit us to see the larger particles. In answer to the problem of how those naturally indivisible particles cohere, he rejects the ancient solution of hooked particles as begging the question, proposing instead some short-range forces modeled on the gravitational force (Query 31). Newton’s speculations about such forces are driven by an absence of any resolution to the problem about cohesion within the corpuscular theory itself.