If there is an ideal city-- and it is by no means clear that Plato believed in its possibility- then
it can and must be ruled by philosophers. In this case the philosopher must live a double life
(as it were): he will practice philosophy and serve as a ruler. To qualify for this position,
an individual must possess individual wisdom and practical virtue; in addition,
he or she must not want top rule or lead a political life. A person who does want to rule is
by definition, not a true philosopher and thus disqualified from ruling. The philosopher
in the ideal city, however, will agree to rule, in spite of his disinclination to do so.
Since he is a "just" person responding to a "just command," the philosopher is "willing"
to return and rule the c ity.
From stone tablets to html code, it's not lost on me.