taken from the following link
Man, God or Creature
Manas is the fifth principle ... that portion of Manas which follows the two higher principles is the ancestral Soul, the bright, immortal thread of the higher Ego, to which clings the spiritual aroma of all the lives and births. For Sutratma is, literally "the thread of spirit," the Immortal Ego, the Individuality which incarnates in man one life after the other, and upon which are strung his countless personalities. Your spiritual "I" is immortal, but from your present self it can carry away into Eternity that only which has become worthy of immortality, namely, the aroma alone of the flower that has been mown by death. Your present "I" is not the body, nor yet is it Manas-Sutratma, but Sutratma Buddhi.
Spirituality is on its ascending arc, and the animal or physical impedes it from steadily progressing on the path of its evolution only when the selfishness of the personality has so strongly infected the real inner man with its lethal virus, that the upward attraction has lost all its power on the thinking reasonable man.
And so the Immortal Ego Project emerged.