This essay starts seeking the Greek word «demagogia» in ancient classical literature. At the beginning, the notion’s conceptual shifts are identified from Plato’s dialogues and from Aristophanes’ comedies: the first meaning of demagoguery is as a strategy of conquest and preservation of political power, which is very evident in democracy. Afterwards, the essay examines the following shades of meaning of the concept, with a focus on the transepochal validity of the characteristics —highlighted above all by Plato— which make the democratic system a particularly fertile ground for demagogic degeneration, far beyond the historical circumstances. After reflecting on Plato’s Republic and Polybius’ Histories, which identify demagoguery as a form of physiological transitional moment between democracy and tyranny, the essay focuses on the dynamic equilibrium between the demagogue and the demos, evident not only in Plato but also in Aristotle. This essay ends with the proposal to build, by extrapolation from classical literature, the ultimate meaning of demagoguery: a theoretical hypothesis of a form of demagogic government.