Q. Who invented the greeting, chag same’ach, or its equivalent, “Good Yom-Tov“?
A. Chag same’ach derives from the Biblical command, v’samachta b’chaggecha – “You shall rejoice in your festival” (Deut. 16:14). The law is that everyone, even a mourner, is obligated by this command. Even when it is difficult to rejoice, one still has to rejoice. Rabbi Yehoshua ben Chananya said, “Rejoicing on a festival is a religious duty” (Pes. 68b).
Some of the sages debated how to rejoice. Rabbi Eliezer said, “Either eat and drink or sit and study”; Rabbi Yehoshua said, “Devote half to God and half to yourselves”. Following his ruling, we fill a festival with both bodily enjoyment, centred around the meal-table, and spiritual experience, through prayer and Torah study.
The greeting, “Good Yom-Tov“, is a somewhat peculiar phrase, since literally it means, “good good day”, but from at least as early as the time of the Mishnah, Yom-Tov was a word on its own with the meaning of “festival”. The tractate Betzah, for example, debates the question of what to do with an egg laid on Yom-Tov, and in the Tosefta, a work analogous to the Mishnah, Betzah is actually called Yom-Tov.
To say “Good Yom-Tov” is not the same thing as to say “Happy Yom-Tov“. Goodness and happiness are not identical. Happiness often connotes having a party, and life limits the amount of partying we can do. Goodness means something different, and in the Jewish view it is better to be good than to be happy.