 The Ability Hypothesis, as it is often called, is more resilient than many philosophers suppose (see Tye 2000, Chapter One). But it has difficulty in properly accounting for our knowledge of what it is like to undergo experiences of determinate hues while we are undergoing them. For example, I can know what it is like to experience red-17, as I stare at a rose of that color. Of course, I don’t know the hue as red-17. My conception of it is likely just that shade of red. But I certainly know what it is like to experience the hue while it is present. Unfortunately, I lack the abilities Lewis cites and so does Mary even after she leaves her cell. She is not able to recognize things that are red-17 as red-17 by sight. Given the way human memory works and the limitations on it, she lacks the concept red-17. She has no mental template that is sufficiently fine-grained to permit her to identify the experience of red-17 when it comes again. Presented with two items, one red-17 and the other red-18, in a series of tests, she cannot say with any accuracy which experience her earlier experience of the rose matches. Sometimes she picks one; at other times she picks the other. Nor is she able afterwards to imagine things as having hue, red-17, or as having that very shade of red the rose had; and for precisely the same reason.