 The atomists accounted for perception by means of films of atoms sloughed off from their surfaces by external objects, and entering and impacting the sense organs. They tried to account for all sensible effects by means of contact, and regarded all sense perceptions as caused by the properties of the atoms making up the films acting on the atoms of animals’ sense organs. Perceptions of color are caused by the ‘turning’ or position of the atoms; tastes are caused by the shape of the atoms contacting the tongue, e.g., bitter tastes by the tearing caused by sharp atoms; feelings of heat are ascribed to friction. Heat itself is said to be caused by the admixture of tiny fire atoms. Democritus considered thought to be a material process involving the local rearrangement of bodies, just as much as is perception.