 In both the Essay and the Treatise Condillac set out to show that all of our cognitive and conative faculties are generated from sensation and can be derived from that operation alone. To this end he identified perception, consciousness, and attention as all being different aspects of the one operation of sensation. Perception is the impression sensation makes upon the mind, consciousness is this impression considered as something experienced by the mind, and attention is simply a more vivid perception. But when Condillac came to account for memory and reminiscence, this project stalled. It is not implausible to maintain that a sensation might continue to be experienced after the object that occasioned it has ceased to act on the sense organ. But such an “echo” of a past sensation is itself a present phenomenon. It might be fainter than other sensations that are now occurring, but being experienced to be faint is not the same thing as being thought to have originated in the past. Rather than explain how sensation can give rise to an awareness of pastness Condillac simply helped himself to the notion. In the Essay, he defined “reminiscence” as the awareness that a perception has been had “before” without anywhere explaining how the idea that one thing can be “before” another could arise simply from sensation (Essay I.ii.1. §15). In the Treatise he distinguished the memory of a sensation from a current sensation by calling the former “weakly sensing what one was (sentir foiblement ce qu’elle a été)” and the latter “vividly sensing what one is (sentir vivement ce qu’elle est).” But then he immediately went on to say that recalled sensations can sometimes be more vivid than current ones (Treatise I.ii.8–9). So what necessarily distinguishes remembered sensation from current sensation, on this account, is just that remembered sensations are of what “was.” But this is not to explain how we could get the idea that a sensation is of what was as opposed to what is. 