we call attention. Our attention is naturally drawn to those perceptions that are most pleasurable or painful, and consequently to those perceptions that we have connected with those that are most pleasurable or painful. Thus, experience of pleasure and pain is what first instructs us where to focus our attention. Learning where to focus attention is important, because many perceptions can be present at once, and a consciousness that is evenly distributed over a great number of perceptions knows none of them very clearly or distinctly (Essay I.ii.1. §§1–14).
Those perceptions that we attend to can seem to drown out the others and produce the illusion that they alone exist, whereas those perceptions that we are less conscious of can be so faint that it is impossible to recall that we have had them the instant after the stimulus that produced them fades. Those perceptions that we attend to can also continue for some time after the stimulus that produced them has ceased. This produces an experience that Condillac referred to as “reminiscence” (réminiscence). An object continuously acting on our sense organs causes us to now experience a particular perception while we are simultaneously conscious of an echo, as it were, of an identical past perception, produced just a moment ago. Condillac's reasoning is less than explicit at this point, but he seems to have taken this experience to provide us with an awareness of what we might call the “pastness” of the echo, and at the same time of the continued existence of an identical self which experienced both the past perception and the current ones. The idea of self is thus not the product of a Cartesian intellectual intuition. Like the idea of one's own extended body and of other extended things, it is discovered through having a particular kind of sensory experience, in this case, the experience of reminiscence (Essay I.ii.1. §15).
In the Essay, Condillac distinguished between reminiscence, understood as the perception that one is perceiving something that one has perceived before, and memory. Memory is not the process of forming an image of something one has experienced before. Condillac instead described it as the process of forming an idea just of signs or circumstances that have been associated with a previously experienced object. The operation of forming an image of a previously experienced object is not memory but “imagination,” or reminiscence, if the imagined object is thought of as one that has been experienced before. (Since signs are not discussed in the Treatise, the distinction between memory and imagination/reminiscence does not appear in that work, and both reminiscence and what the Essay calls vivid imagination are named “memory.” However, it is not clear that this is a doctrinal shift as opposed to a mere change of emphasis mandated by the different project of the Treatise.) Imagination becomes possible once a perception has become familiar from a number of previous experiences, which give the mind a facility to repeat that perception at will. The operation of imagination is enhanced if the perception is simple, composed of simple parts that are organized in accord with some guiding principle that can be invoked in reconstructing it, or customarily connected with other, presently occurring perceptions. Since connections with other, customarily connected perceptions need to be noticed, and attention is a function of need, which is in turn established by past experience of pleasure and pain, imagination is ultimately a function of past experience. The same can be said of memory, with the qualification that, insofar as memory involves the recollection of signs, its operation also presupposes the ability to make use of signs (Essay I.ii.2–3, Treatise I.ii).
Like Reid after him, Condillac drew a distinction between three kinds of signs: accidental, natural, and instituted (Essay I.ii.4).
Accidental signs are objects or circumstances that have been frequently encountered in conjunction with an object, so that the occurrence of the former induces the mind to imagine the