A similar comparison is put into the mouth of Sokrates himself by Plato in the Theætêtus, p. 174 D.
[23] Plato, Republic, i. pp. 343-344.
Position laid for the subsequent debate and exposition.
Thrasymachus is described as laying down this position in very peremptory language, and as anxious to depart immediately after it, if he had not been detained by the other persons present. His position forms the pivot of the subsequent conversation. The two opinions included in it — (That justice consists in obedience yielded by the weak to the orders of the strong, for the advantage of the strong — That injustice, if successful, is profitable and confers happiness: justice the contrary) — are disputed, both of them, by Sokrates as well as by Glaukon.[24]
[24] Plato, Repub. i. pp. 345 A-348 A.
Arguments of Sokrates — Injustice is a source of weakness — Every multitude must observe justice among themselves, in order to avoid perpetual quarrels. The same about any single individual: if he is unjust, he will be at war with himself, and perpetually weak.
Sokrates is represented as confuting and humiliating Thrasymachus by various arguments, of which the two first at least are more subtle than cogent.[25] He next proceeds to argue that injustice, far from being a source of strength, is a source of weakness — That any community of men, among whom injustice prevails, must be in continual dispute; and therefore incapable of combined action against others — That a camp of mercenary soldiers or robbers, who plunder every one else, must at least observe justice among themselves — That if they have force, this is because they are unjust only by halves: that if they were thoroughly unjust, they would also be thoroughly impotent — That the like is true also of an individual separately taken, who, so far as he is unjust, is in a perpetual state of hatred and conflict with himself, as well as with just men and with the Gods: and would thus be divested of all power to accomplish any purpose.[26]
[25] Plato, Republic, i. pp. 346-350.
[26] Plato, Republic, i. pp. 351-352 D.
Farther argument of Sokrates — The just man is happy, the unjust man miserable — Thrasymachus is confuted and silenced. Sokrates complains that he does not yet know what Justice is.