Why Plutarch reads him
Plutarch reads Alcibiades as the supreme case of the ungoverned gift — a man endowed by nature with everything that should make a great statesman, and ruined by the one thing he lacked, the self-command to govern it. Ward of Pericles, companion of Socrates, the most beautiful and gifted man of his Athenian generation, Alcibiades had ability, charm, courage and eloquence in abundance. The platform reads him, with Plutarch, not for the biography of his betrayals but for what he shows about the relation of character to power: that talent without character is not a lesser virtue but a danger.
Character: the chameleon
Plutarch's portrait turns on Alcibiades' extraordinary adaptability — his power to become whatever each setting required. At Sparta he out-Spartaned the Spartans, living hard and plain; at the Persian court he outdid the Persians in luxury and flattery; at Athens he was the brilliant democrat. The platform reads this chameleon quality as the heart of Plutarch's moral interest: it is the mark of a man with no fixed centre, whose genius for pleasing concealed the absence of any loyalty deeper than his own advancement. The same gift that made him irresistible made him incapable of fidelity to anything but himself.
The political significance
Alcibiades' career is, in Plutarch's hands, a study in what such a man does to a city. He pressed Athens into the catastrophic Sicilian Expedition, then — recalled to face trial — defected to Sparta and gave the enemy the counsel that broke Athenian power; he intrigued with Persia; he returned to Athens in triumph and was driven out again. The platform reads his life as inseparable from Athens' ruin in the Peloponnesian War: the city's most gifted son was also a principal agent of its destruction, and the tragedy is that the two facts were one. His ambition served no master, and so it served no city.
The lesson Plutarch draws
The platform reads Plutarch's Alcibiades as the cautionary half of the education in virtue and ambition. The lesson is not that ability is dangerous but that ability is neutral — that it takes its moral direction entirely from the character that wields it, and that a republic which dazzles itself with a gifted man's talents while ignoring his lack of virtue is preparing its own betrayal. Plutarch pairs him with the Roman Coriolanus, another great gift turned against its own city, to set the pattern in relief.