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.

When we come to images or memories or thoughts, speculation, while always closely related to practice, is more explicit, and it is in fact not immediately obvious that such processes can be described in any sense as practical.

The interval between a cold expectation and a warm desire may be filled by expectations of varying degrees of warmth or by desires of varying degrees of coldness.

For psychological purposes the most important differences in conation are those in virtue of which the object is revealed as sensed or perceived or imaged or remembered or thought.

The mental act of sensation which issues in reflex movement is so simple as to defy analysis.

But though cognition is not an element of mental action, nor even in any real sense of the word an aspect of it, the distinction of cognition and conation has if properly defined a definite value.

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