left behind his self divides and creates idols of itself. The supreme self just wants to be left alone like zeus, but is forced back to put an end to this nonsense. The whole self is brought back to 'realise' itself in its false reflections. all this was later spelt out by Jung
The cave of plato is about how to transcend illusion in order reach truth but not, as many assume, ( other than Nietzsche who gets it) to replace illusion with a higher truth, instead to bring an end to illusion, replacing it with 'matter of fact truth'.
It is in fact the illusion that is considered higher by the inhabitants of the cave and with Plato's story people refuse to accept this materialist interpretation. Nietzsche parodys the story by leaving his own self in the cave and traveling up to the mountain.