Thus the same object may supply a practical perception to one person and a speculative one to another, or the same person may perceive it partly practically and partly speculatively.

You can mark in desire the rising of the tide, as the appetite more and more invades the personality, appealing, as it does, not merely to the sensory side of the self, but to its ideal components as well.

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.

Desire then is the invasion of the whole self by the wish, which, as it invades, sets going more and more of the psychical processes; but at the same time, so long as it remains desire, does not succeed in getting possession of the self.

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.

Thus the same object may supply a practical perception to one person and a speculative one to another, or the same person may perceive it partly practically and partly speculatively.