In the perception of a tree we can distinguish the act of experiencing, or perceiving, from the thing experienced, or perceived.

Psychology is the science of the act of experiencing, and deals with the whole system of such acts as they make up mental life.

The thing of which the act of perception is the perception is experienced as something not mental.

What is the meaning of the togetherness of the perceiving mind, in that peculiar modification of perceiving which makes it perceive not a star but a tree, and the tree itself, is a problem for philosophy

We cannot therefore say that mental acts contain a cognitive as well as a conative element.

Such being the nature of mental life, the business of psychology is primarily to describe in detail the various forms which attention or conation assumes upon the different levels of that life.

The perceptive act is a reaction of the mind upon the object of which it is the perception.