“Some characteristic expressions he used rather frequently in everyday speech can be seen in letters in his own hand, in which he sometimes writes, when he wants to say that certain men will never pay: "they'll pay on the Greek Kalends." And when he wants to encourage his addressee to put up with present circumstances whatever they are, he says: "Let us be satisfied with the Cato we have."”
Cotidiano sermone quaedam frequentius et notabiliter usurpasse eum, litterae ipsius autographae ostentant, in quibus identidem, cum aliquos numquam soluturos significare vult, "ad Kalendas Graecas soluturos" ait; et cum hortatur ferenda esse praesentia, qualiacumque sint: "contenti simus hoc Catone".
Source: The Twelve Caesars, Augustus, Ch. 87