In vino veritas is a Latin phrase that means "in the wine is the truth", used as a proverb to express the feeling of “freedom” caused by alcohol.
The full expression of this Latin expression would be in vino veritas, in aqua toilets, which means “in wine is the truth, in water is health”.
According to history, the probable author of this proverb for Latin would be the philosopher Caio Pliny Cecílio Segundo, better known as “Pliny the Elder”.
By this expression, the ancient Romans meant that when people who are under the influence of wine (alcohol), they lose their shame and make the truths to be revealed.
For the Roman historian Tacitus, people can never lie effectively when they are drunk, leading to believe that what they reveal when they are under the influence of alcoholic beverages is truth.
Some researchers believe that the origin of this proverb is Greek, created by the lyric poet Alceu de Mytilene, and that it was only translated by Pliny the Elder into Latin.
The philosopher Plato would have mentioned this expression in “The Banquet”, a series of discourses of Platonic ideas about nature and love.
See also the meaning of Omnia vincit and others latin phrases.