The main substance of this dialogue consists of a discussion, carried on by Sokrates with Nikias and Lachês, respecting Courage. Each of the two latter proposes an explanation of Courage: Sokratês criticises both of them, and reduces each to a confessed contradiction.

Lachês. Subject and persons of the dialogue—whether it is useful that two young men should receive lessons from a master of arms. Nikias and Lachês differ in opinion

The discussion is invited, or at least dramatically introduced, by two elderly men—Lysimachus, son of Aristeides the Just,—and Melêsias, son of Thucydides the rival of Perikles. Lysimachus and Melêsias, confessing with shame that they are inferior to their fathers, because their education has been neglected, wish to guard against the same misfortune in the case of their own sons: respecting the education of whom, they ask the advice of Nikias and Lachês. The question turns especially upon the propriety of causing their sons to receive lessons from a master of arms just then in vogue. Nikias and Lachês, both of them not merely distinguished citizens but also commanders of Athenian armies, are assumed to be well qualified to give advice. Accordingly they deliver their opinions: Nikias approving such lessons as beneficial, in exalting the courage of a young man, and rendering him effective on the field of battle: while Lachês takes an opposite view, disparages the masters of arms as being no soldiers, and adds that they are despised by the Lacedæmonians, to whose authority on military matters general deference was paid in Greece. Sokratês,—commended greatly by Nikias for his acuteness and sagacity, by Lachês for his courage in the battle of Delium,—is invited to take part in the consultation.