As Socrates defends the idea of philosopher kings, he finds that he must explain the nature of philosophy itself. In order to do this, however, he must also share his conception of ultimate reality. It is unclear to what extent this conception belongs to Socrates or Plato, but it is set forth by Plato's character named Socrates, and it is to this character that I refer when I mention Socrates.
In the Greek philosophical tradition, numerous philosophers had articulated metaphysical theories. Socrates presents his view above and against these previous conceptions. Among the Pre-Socratics, Heraclitus, Parmenides, and Empedocles perhaps present the most important problems for Socrates to address with his theory.
Particularly, Socrates must address the Heraclitan contradictions of change and permanence, unity and plurality, and being and non-being. Socrates resolves these contradictions by postulating the existence of a higher reality. In the intelligible realm, the forms are immutable and truly possess being. Moreover, Socrates is able to allow for both unity and plurality because the forms participate in the prime form of the Good. In the visible realm, things are able to change because they do not possess perfect being, though they participate in the various forms. Hence these two realms allow Socrates to resolve the apparent contradictions highlighted by Heraclitus.
Similarly, Socrates theory includes the force of attraction which was present in Hesiod and later in Empedocles as well. For Hesiod, Eros brings together Chaos. For Empedocles, Love and Strife are the driving forces behind the cosmos. Attraction plays a somewhat different role in Socrates' account. Socrates states that the Good desires what is Good. Similarly, the forms which participate in the Good desire the good insofar as they participate in it. This tendency exists even in humans, which are particular, because humans desire what is good, though the good is often misconceived.
Socrates addresses many of the problems demonstrated in previous cosmologies and metaphysical theories. He attempts to resolve many of the apparently contradictory features of reality such as change and permanence. He also incorporates the notion of attraction or desire which has its sources in the mytho-poetic tradition. His theory presents a unique solution to metaphysical problems as well as an extensive vision of the true nature of reality.