It is convenient to distinguish the two kinds of experience which have thus been described, the experienc-ing and the experienc-ed, by technical words.

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

But unfortunately Locke treated ideas of reflection as if they were another class of objects of contemplation beside ideas of sensation.

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.

An object is not first imagined or thought about and then expected or willed, but in being actively expected it is imagined as future and in being willed it is 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.