On the festivals, there is a special mitzvah (divine commandment), ???One who locks the doors of his courtyard, and . . . does not feed the poor and the embittered soul???this is not the joy of a mitzvah, but the joy of his belly . . .??????And you shall rejoice on your festival . . .??? (Deuteronomy 16:14), and, our sages explain, the only true joy is shared joy.