Plato's theory on the mind begins before birth, starting at the enlightened heaven of knowledge. A baby is born, and within the child is the knowledge of true reality. This reality is then lost but can be regained through education. Plato states.
" Power and capacity of learning exists in the soul already; and that just as the eye was unable to turn from darkness to light without the whole body, so too the instrument of knowledge can only by the movement of the whole soul be turned from the world of becoming in to that of being" (Pg. 320 pp. 45).
As for this child the preconceived notion of "being" is in fact not true reality. The "reality" is literally nothing but "shadows of images." Plato then progresses to the notion that if this child was enlightened, obtaining true reality, then returned to the former "reality" with the knowledge that he could not act rationally because he would be persecuted from his peers merely for the fact that they do not understand. But to support his major premises that knowledge is relearned he states that if honors and glories were given to men of the "reality" to what the future hold is guessing the patterns of shadows on walls, the ascending child/man would not partake in such events. The ascending child/ man would rather "suffer anything that entertain theses false notions and live in the miserable manner" (pg. 318 pp.31). From here Plato classifies how an enlightened one can turn course from understanding the good and beautiful to one who has seen the light of reality but fights to prove these visions aren't reality. Plato believes this happens because the enlightened one relies to steadily on that of the sensory when in fact his soul has not been turned to be enlightened as well. He is then turned in the wrong direction torn between truth and darkness. This is where people become ill informed and become prisoners of the world to sight.
Plato assures his opinion that "in the world of knowledge the idea of good appears last of all, and is seen only with effort and the immediate source of reason and truth in the intellectual" (pg.