trary evidence by claiming that it would take some time for newly sighted subjects to learn how to focus the eyes in order to perceive colours distinctly, and so to see their outlines. It would then take time for the subjects to attend to the shapes that distinctly seen colours exhibit, since we can expect that at first they would be overwhelmed and confused by the variety of information presented by the eyes, much like a person gaining a first glimpse of a Bosch painting. Finally, even after they came to see colours as, say, outlining square or round shapes, they might still hesitate to assume that simply because an object looks to have a certain shape, that therefore it must be felt to have that shape as well. For all of these reasons, time might pass and the subject might appear to be learning to associate visual experiences with tangible objects, even though the colours that are originally seen are already extended and shaped in three dimensions (Essay I.vi. §16).
Condillac's reply to the Chesselden data contained the germs of an insight that was to be central for the later Treatise: the claim that visual sensations, and indeed all sensations, might contain information that goes unnoticed by a subject simply because it is not attended to. This insight, already present in the Essay, was subversive. It challenged that work's rejection of perception by means of unconscious sensations and unconscious inferences. It led to the Treatise's claim that having a sensation does not imply being conscious of everything that sensation involves (Treatise I.xi.8, III.iii.6).
In his Logic, Condillac illustrated this point by asking his readers to imagine a group of people who travel by night to a chateau situated on a high point before a vast panorama of fields, mountains, cities, towns, and forests. At dawn, the windows are thrown open for just an instant. In that instant, each member of the company experiences a compound visual sensation consisting of multiple, simultaneously present colour patches disposed in space so as to depict all the parts of the panorama that lies out in a particular direction. But from the view obtained in just an instant, no one can say what it was that they saw. If the shutters are left open for more than an instant nothing new is presented to the company. That is, they do not have any sensation they did not have in the first instant. They come to perceive what it is they at first already sensed by selectively attending to each of its parts in turn and then noting how these parts are related to one another (Logic, Part I, Chapter ii).
Condillac had always appreciated that this act of attention is not an innate operation, any more than such higher cognitive operations as abstraction, judgment, or reasoning are innate operations. We need to learn how to attend to what we sense. Experience itself serves as our teacher. The operation of attention is invoked by our needs and interests. We attend first to what promises to satisfy our needs and interests, which are always with us and which always direct our thought. Our knowledge of what promises to satisfy our needs and interests is a product of past experience, which has made us aware of what objects are connected with the frustration or satisfaction of those needs and interests. The needs and interests themselves are developed as a consequence of a past experience of pleasure and pain, which in turn are intrinsic features not just of tactile experience, but of all of our sensations. However, in the Essay Condillac had not appreciated the full implications of this view. Recognizing those implications required being more careful about specifying what is originally given in sensation, what is originally attended to, and what leads us to attend to anything else. The device of the slowly animated “statue” was invoked to assist in making these determinations.
Condillac supposed that the most primitive form of experience would be the sense of smell. A being (Condillac's “statue”) endowed with just this one sense but no motive power would, Condillac supposed, be capa