That is to say, Lower Manas operating through the brain is at once altered into the shape and other characteristics of any object, mental or otherwise. This causes it to have four peculiarities. First, to naturally fly off from any point, object, or subject; second, to fly to some pleasant idea; third, to fly to an unpleasant idea; fourth, to remain passive and considering naught. The first is due to memory and the natural motion of Manas; the second and third are due to memory alone; the fourth signifies sleep when not abnormal, and when abnormal is going toward insanity. These mental characteristics all belonging to Lower Manas, are those which the Higher Manas, aided by Buddhi and Atma, has to fight and conquer. Higher Manas, if able to act, becomes what we sometimes call Genius; if completely master, then one may become a god. But memory continually presents pictures to Lower Manas, and the result is that the Higher is obscured. Sometimes, however, along the pathway of life we do see here and there men who are geniuses or great seers and prophets. In these the Higher powers of Manas are active and the person illuminated. Such were the great Sages of the past, men like Buddha, Jesus, Confucius, Zoroaster, and others. Poets, too, such as Tennyson, Longfellow, and others, are men in whom Higher Manas now and then sheds a bright ray on the man below, to be soon obscured, however, by the effect of dogmatic religious education which has given memory certain pictures that always prevent Manas from gaining full activity.
The Ocean of Theosophy p.56-57