ABSTRACT
Perception: an intentional act To understand how custom brings about the visual perception of the three dimensional world, however, we must first understand the nature of perception itself. First of all, we must distinguish between sensation, which is an original operation of the mind and perception which, in the case of acquired perceptions, is not original but is the result of custom. The distinction between sensation and perception is based on the fact that sensation is not intentional, that is, has no object, while perception is intentional, though grammar might mislead into thinking the opposite.
