  Democritus' theory of perception depends on the claim that eidôla or images, thin layers of atoms, are constantly sloughed off from the surfaces of macroscopic bodies and carried through the air.  Later atomists cite as evidence for this the gradual erosion of bodies over time.  These films of atoms shrink and expand; only those that shrink sufficiently can enter the eye.  It is the impact of these on our sense organs that enables us to perceive. Visible properties of macroscopic objects, like their size and shape, are conveyed to us by these films, which tend to be distorted as they pass through greater distances in the air, since they are subject to more collisions with air atoms.  A different or complementary account claims that the object seen impresses the air by the eidôla, and the compacted air thus conveys the image to the eye (DK 68A135; Baldes 1975).  The properties perceived by other senses are also conveyed by contact of some kind.  Democritus' theory of taste, for example, shows how different taste sensations are regularly produced by contact with different shapes of atoms: some atoms are jagged and tear the tongue, creating bitter sensations, or are smooth and thus roll easily over the tongue, causing sensations of sweetness.