Man is least himself when he talks in his own person. Give him a mask, and he will tell you the truth.

This quote means that people are more likely to be honest and truthful when they are not speaking directly as themselves. For example, if someone was to wear a disguise or mask, they might speak more freely and be more honest. In other words, when speaking as themselves, people may not always tell the truth and may not be entirely honest about how they are feeling or what they are thinking.