"Energy follows thought" is a basic tenet of the Raja Yoga system and is true even where these images of fancy are concerned. These fancied images fall primarily into three groups, which the student would do well to consider.

1. Those thought forms which he constructs himself, which have an evanescent life and which are dependent upon the quality of his desires; being therefore neither good nor evil, low nor high, can be vitalized by low tendencies or idealistic aspirations, with all the intermediate stages to be found between these extremes. The aspirant has to guard himself in order that he may not mistake these for reality. An illustration might well be given here, in respect to the facility with which people judge they have seen one of the Brothers (or Masters of the Wisdom), whereas all they have perceived is a thought form of one of Them; the wish being father to the thought they are the victim of that form of incorrect perception called by Patanjali, fancy.
2. Those thought forms which are created by the race, the nation, the group or the organization. Group thought forms of any kind (from the planetary form to that constructed by any band of thinkers) form the sum total of the "great illusion!" Herein lies a hint to the earnest aspirant.
3. That thought form created by a man since his first appearance in physical form, and called the "Dweller on the Threshold!" Being created [21] by the lower personal self and not by the soul, it is impermanent and is simply held together by the man's lower energy. When the man begins to function as the soul this "image" he has created, through his "fancy" or his reaction to delusion, is dissipated by a supreme exertion. It has no real existence once there is nothing in the aspirant to feed it, and the realization of this enables him to free himself from its thralldom.