may seem to wear a family likeness, like the two friends Simmias
and Cebes in the Phaedo. But on a nearer examination of them
the similarity vanishes, and they are seen to be distinct characters.
Glaucon is the impetuous youth who can "just never have enough of fechting"
(cf. the character of him in Xen. Mem. iii. 6); the man of pleasure
who is acquainted with the mysteries of love; the "juvenis qui
gaudet canibus," and who improves the breed of animals; the lover
of art and music who has all the experiences of youthful life.
He is full of quickness and penetration, piercing easily below
the clumsy platitudes of Thrasymachus to the real difficulty;
he turns out to the light the seamy side of human life, and yet
does not lose faith in the just and true. It is Glaucon who seizes
what may be termed the ludicrous relation of the philosopher
to the world, to whom a state of simplicity is "a city of pigs,"
who is always prepared with a jest when the argument offers him
an opportunity, and who is ever ready to second the humor of Socrates
and to appreciate the ridiculous, whether in the connoisseurs of music,
or in the lovers of theatricals, or in the fantastic behavior of
the citizens of democracy. His weaknesses are several times alluded
to by Socrates, who, however, will not allow him to be attacked
by his brother Adeimantus. He is a soldier, and, like Adeimantus,
has been distinguished at the battle of Megara.

The character of Adeimantus is deeper and graver, and the profounder
objections are commonly put into his mouth. Glaucon is more demonstrative,
and generally opens the game. Adeimantus pursues the argument further.
Glaucon has more of the liveliness and quick sympathy of youth;
Adeimantus has the maturer judgment of a grown-up man of the world.
In the second book, when Glaucon insists that justice and injustice
shall be considered without regard to their consequences,