It was during the archonship of Megacles (a scion of the great Alcmaeonic family, which boasted its descent from Nestor) that the aristocracy was menaced by the ambition of an aristocrat.
Born of an ancient and powerful house, and possessed of considerable wealth, Cylon, the Athenian, conceived the design of seizing the citadel, and rendering himself master of the state.

He had wedded the daughter of Theagenes, tyrant of Megara, and had raised himself into popular reputation several years before, by a victory in the Olympic games (B.C.

640).

The Delphic oracle was supposed to have inspired him with the design; but it is at least equally probable that the oracle was consulted after the design had been conceived.

The divine voice declared that Cylon should occupy the citadel on the greatest festival of Jupiter.