I argue that Plato, in the Timaeus , draws deep theoretical distinctions between sensation and affect, which comprises pleasure, pain, desire and emotion. Sensation (but not affect) is both 'fine-grained' (having orderly causal connections with its fundamental explanatory items) and 'immediate' (being provoked absent any mediating psychological state). Emotions, by contrast, are mediated and coarse-grained. Pleasure and pain are coarse-grained but, in a range of important cases, immediate. The Theaetetus assimilates affect to sensation in a way the Timaeus does not. Smell frustrates Timaeus because it is coarse-grained, although unlike pleasure and pain it is so by accident of physiology.