 Epicurus now has in place the fundamental constituents of his natural world, and he might have stopped here, with atoms and void and the denial, on the grounds of inconceivability, of any other kind of basic physical principle. All secondary properties, such as color and taste, will be explained as epiphenomena of atomic combinations, and perception of things at a distance by the continual emission of infinitesimally thin laminas from objects, which maintain the relevant features of the source (in the case of vision, for example, the laminas will preserve the atomic patterns specific to the color and shape of the object) and directly stimulate the relevant sense organ. This is a tricky thesis, and again posed puzzles: how do the lamina or simulacra, as Lucretius called them, of a mountain enter the eye, for example? In fragments? By somehow shrinking? We do not know the answer to this one, but there are some plausible hypotheses (see Leone 2012; Konstan 2020). A few more concepts fill in the picture of the natural world: thus, Epicurus denies that there can be infinitely many kinds of atoms, for then all shapes (which define the kinds) at any given magnitude would be exhausted and atoms would have to reach visible proportions, which we know that they do not (this argument depends on the idea of minima, discussed further below); instead, the number of kinds (i.e., shapes of various microscopic sizes) is inconceivably large but “not strictly infinite,” whereas the number of each kind of atom is simply infinite (LH 55–56). This condition is also invoked to explain why there is a limit on possible types of combinations of atoms, and hence on the number of viable species of things in the perceptible world: if there were infinitely many kinds of atoms, Epicurus believed, they could combine to generate absolutely anything — an infinity of different sorts of thing.