To see things is to perceive what they afford: James J. Gibson's concept of affordance

Gibson distinguishes among the properties of environmental things their affordances, which he identifies in terms of that which a thing offers an animal for good or ill. In large part, this article considers his conception of environmental affordances and visually perceiving them, with special attention to the concept of affordance that he exercises in the presentation of his conception. Particular emphasis is placed here on the distinction between the affordance properties of things themselves, and what it is that these things afford an animal, what they enable owing to those properties, and the proposal that the affordances of environmental things are not experiential; they are not properties of the perceptual experiences produced in the process of perceiving them. This does not deny that experiences themselves too possess affordance properties — for example, they are such as to enable specific behaviors — but these affordances are not that which is perceived, according to Gibson, when engaged in the activity of straightforward perceiving. The stream of perceptual experience that is part and product of the latter activity is at all points outwardly directed, not directed upon itself