One of the greatest discoveries of modern times is the impellent energy of thought.

That every idea in consciousness is energizing and carries with it an impulse to some kind of muscular activity is a comparatively new but well-settled principle of psychology. That this principle could be made to serve practical ends seems never to have occurred to anyone until within the last few years.

Certain eminent pioneers in therapeutic psychology, such men as Prince, Gerrish, Sidis, Janet, Binet and other physician-scientists, have lately made practical use of the vitalizing influence of certain classes of ideas in the healing of disease.

We shall go farther than these men have gone and show you that the impellent energy of ideas is the means to all practical achievement and to all practical success.

Preceding books in this Course have taught that—

I. All human achievement comes about through some form of bodily activity.

II. All bodily activity is caused, controlled and directed by the mind.

III. The mind is the instrument you must employ for the accomplishment of any purpose.

You have learned that the fundamental processes of the mind are the Sense-Perceptive Process and the Judicial Process.

So far you have considered only the former—that is to say, sense-impressions and our perception of them. You have learned through an analysis of this process that the environment that prescribes your conduct and defines your career is wholly mental, the product of your own selective attention, and that it is capable of such deliberate molding and adjustment by you as will best promote your interests.

But the mere perception of sense-impressions, though a fundamental part of our mental life, is by no means the whole of it. The mind is also able to look at these perceptions, to assign them a meaning and to reflect upon them. These operations constitute what are called the Judicial Processes of the Mind.

The Judicial Processes of the Mind are of two kinds, so that, in the last analysis, there are, in addition to sense-perceptions, two, and only two, types of thought.

One of these types of thought is called a Causal Judgment and the other a Classifying Judgment.