En vino, veritas.

In, not en, and it is written without the comma.

(Finally the two years of suffering through Latin classes have paid off!)

The book I’m reading (Incognito by David Eagleman) mentioned exactly that.

Robinson and Yarvitz, like many others, suspected that the alcohol had loosened Gibson’s inhibitions and revealed his true self. And the nature of their suspicion has a long history: the Greek poet Alcaeus of Mytilene coined a popular phrase En oino álétheia (In wine there is the truth), which was repeated by the Roman Pliny the Elder as In vino veritas. The Babylonian Talmud contains a passage in the same spirit: “In came wine, out went a secret.” It later advises, “In three things is a man revealed: in his wine goblet, in his purse, and in his wrath.” The Roman historian Tacitus claimed that the Germanic peoples always drank alcohol while holding councils to prevent anyone from lying.

But there are many things that people have “known” for years that turned out to be untrue as our ability to understand the physical world increased. Now we’re finding that our unconscious mind accounts for more of what we think than our conscious mind can control.