 One consequence of Locke’s treatment of attention as a mode of thinking is that, once we have a theory of thinking before us, we need no further theory to account for the possibility of attention, contemplation, study, etc. (Just as, to use the classic example of ‘modes’, we need no substantive independent theory, once we have a theory of walking, to explain the possibility of limping, pacing or ambling.) We need to say something in giving an analysis of the nature of modes, but—once the thing-to-be-modified has been accounted for—our analysis can simply say something brief, along the lines indicated by Locke. We do not need to give a theory that postulates any substances or processes specific to the explanation of attention.