This paper draws attention to the studies of Michel Foucault on parrhesia as a critical practice of truth-telling situated in the Greek antiquity. Moreover, this paper tries to consider some connections between the revolution (as a dramatic event), as it is understood from Foucault's reading of Kant's 'Was ist Aufklarung?' and parrhesia as a critical attitude towards truth and truth-telling and in opposition to rhetoric discourse. The underlying presupposing of this paper consists in the fact that in the Greek antiquity, the relationship between parrhesia, as a critical attitude, and rhetoric discourse reached a very tense moment.