ABSTRACT
As already stated, perceptual activities give rise to new structures and thereby, in general, to a quantitative diminution of primary illusions. But these activities are, in turn, indirect causes of fresh illusions, in so far as they lead to the relating of hitherto unrelated elements which are separated in space or time. These relations give rise to deformations which are analogous to primary effects but which increase with age, being dependent upon those developing activities, which thus become their indirect causes. In the following chapter, the most important of these activities and the illusions associated with them will be described.
