Unsurprisingly, Plato values knowledge with the highest esteem. In Book VI of Plato’s Republic, Socrates explains why philosophers are the ideal rulers and not vicious or useless if raised under the right circumstances. Socrates doesn’t believe that it is at the fault of philosophy if philosophers are perceived as useless, and expresses this idea with an analogy of a ship crew. He likens the “useless” philosopher king as a shipowner afflicted with weak hearing and short-sightedness. Although the sailors may all be in a physically better condition than the shipowner, and even though they are occasionally able to seize control of the ship by force and cunning, they have never learned the art of navigation and are therefore unable to efficiently rule the ship. The philosopher is thus best suited for rule as they are enlightened with the knowledge on how to do so.
Accordingly, Socrates believes that for the ideal guardians to thrive, they must be reared under an ideal constitution, but that such a constitution does not yet exist and therefore the guardian can not exist either. Here we have no other evidence to cling to except Socrates’ belief that the ideal ruler can exist, and that if they did we would all agree with Socrates wholeheartedly.
Book VI also delves into some of Plato’s most abstract ideas. He illustrates his idea on the Form of the Good through an analogy of the Sun. As we could not see anything in our world without the light of the sun, so too could we not see the good in anything without the original Form of the Good. Socrates uses analogy to express this idea for reasons not fully known. Could it be that it is not an idea any of us could fathom? Is it more important for anyone who is to be enlightened to come upon this realization independently? Nonetheless, this metaphysical mystery is the key to the philosopher king’s divine right to rule according to Socrates, as it is with this knowledge of the Form of the Good that philosophers are inextricably tied, and therefore rendered just.