We have seen that the mental body is so closely mingled with the astral, that they act as a single body, but the dawning mental faculties add to the astral passions a certain strength and quality not apparent in them when they work as purely animal qualities. The impressions made on the mental body are more permanent than those made on the astral, and they are consciously reproduced by it. Here memory and the organ of imagination begin, and the latter gradually moulds itself, the images from the outer world working on the matter of the mental body and forming its materials into their own likeness.
These images, born of the contacts of the senses, draw round themselves the coarsest mental matter; the dawning powers of consciousness reproduce these images, and thus accumulate a store of pictures that begin to stimulate action initiated from within, from the wish to experience again through the outer organs the vibrations that were found pleasant, and to avoid those productive of pain. The mental body then begins to stimulate the astral, and to arouse in it the desires that, in the animal, slumber until awaked by a physical stimulus; hence we see in the undeveloped man a persistent pursuit of sense-gratification never found in the lower animals, a lust, a cruelty, a calculation to which they are strangers.
The dawning powers of the mind, yoked to the service of the senses, make of man a far more dangerous and savage brute than any animal, and the stronger and more subtle forces inherent in the mental spirit-matter lend to the passion-nature an energy and a keenness that we do not find in the animal-world. But these very excesses lead to their own correction by the sufferings which they cause, and these resultant experiences play upon the consciousness and set up new images on which the imagination works. These stimulate the consciousness to resist many of the vibrations that reach it by way of the astral body from the external world, and to exercise its volition in holding the passions back instead of giving them free rein.
Such resistant vibrations are set up in, and attract towards the mental body, finer combinations of mind-stuff, and tend also to expel from it the coarser combinations that vibrate responsively to the passional notes set up in the astral body; by this struggle between the vibrations set up by passion-images and the vibrations set up by the imaginative reproduction of past experiences, the mental body grows, begins to develop a definite organization, and to exercise more and more initiative as regards external activities.
While the earth-life is spent in gathering experiences, the intermediate life is spent in assimilating them, as we shall see in detail in the following chapter, so that in each return to earth the Thinker has an increased stock of faculties to take shape as his mental body. Thus the undeveloped man, whose mind is the slave of his passions, grows into the average man, whose mind is a battleground in which passions and mental powers wage war with varying success, about balanced in their forces but who is gradually gaining the mastery over his lower nature.
***From Annie Besant – The Ancient Wisdom