I argue that Democritus presents a theory of colour in which the predominance of atomic shapes and microstructural arrangements are necessary but not sufficient for colour vision. Focusing primarily on Democritus’ basic colours, I analyse his microstructural account, providing a new analysis of the natural and technological underpinnings of his method of explanation. I argue that the notion of predominance allows Democritus to account for both the variation and the repeatable correspondence of colour perception by setting limits on possible microstructures. (...) This account, however, is complicated by the evidence for a Democritean theory of colour transformation and distorted vision, which arise from a dynamic interplay of features at the level of microstructures and at the level of perception. (shrink)