  In a second line of Lucretian reasoning, Gassendi argues that atoms are the primary principles of matter on the grounds that some fundamental material elements must be impenetrable if we are to account for varying degrees of resistance in macro-sized objects. He suggests that since all material things resist pressure to some extent, they all have one or another degree of solidity. The only way to explain this range of solidity, or resistance to pressure, he claims, is by supposing that the ultimate constituent elements of all bodies are not soft, which is guaranteed if they are all solid. Otherwise, there could be no bodies harder than the softest ones, for if the ultimate constituent elements were soft, then more solid bodies could never be composed from them. From this he concludes that all material things must be composed of maximally hard elements which, when put together with more empty space between them, yield softer bodies—and, when put together with less empty space between them, yield harder bodies.