In vino veritas is a Latin phrase that translates, “in wine [there is the] truth". It is also known as a Greek phrase “Ἐν οἴνῳ ἀλήθεια” En oino álétheia, which has the same meaning. The author of the Latin phrase is Pliny the Elder; the Greek phrase is attributed to the Greek poet Alcaeus. A more proper form of the phrase is "In vino veritas est". The word est is, however, often omitted.
The Greek poet Alcaeus is the oldest known source for the phrase. The Roman historian Tacitus described how the Germanic peoples always drank wine while holding councils, as they believed nobody could lie effectively when drunk.
The phrase is often continued as, "In vino veritas, in aqua sanitas", i.e., "In wine there is truth, in water there is health."
Similar phrases exist across cultures and languages. In Chinese, there is the saying, "酒後吐真言" ("After wine blurts truthful speech"). The Babylonian Talmud (תלמוד בבלי) contains the passage: "נכנס יין יצא סוד", i.e., "In came wine, out went the essence."
It continues, "בשלשה דברים אדם ניכר בכוסו ובכיסו ובכעסו", i.e., "In three things is a man revealed: in his wine goblet, in his purse, and in his wrath." (In the original Hebrew, the words for "his goblet", "his purse", and "his wrath" rhyme and are a play on words all using the root "כס".)
In the 1770s, Benjamin Cooke wrote a glee by the title of In Vino Veritas. His lyrics [with modern punctuation, etc.] are as follows:
Round, round with the glass, boys, as fast as you can,
Since he who don't drink cannot be a true man.
For if truth is in wine, then 'tis all but a whim
To think a man's true when the wine's not in him.
Drink, drink, then, and hold it a maxim divine
That there's virtue in truth, and there's truth in good wine!