Q. What is the meaning of the Yiddish phrase, Alle Montag un Donnershtag – “every Monday and Thursday”?
A. It means “constantly”. It comes from the practice of reading the Torah on Monday and Thursday mornings. In ancient times these were market days when people from outlying farms and villages came to the nearest town. As well as buying and selling, they were able to attend synagogue services and be assured of a minyan, and as pious Jews they were delighted to have the opportunity of hearing the Torah reading.
The Midrash links the practice with the people’s complaint in the wilderness that they had gone three days without water (Ex. 15:22). “Water” means “Torah”. Just as people need physical water to drink, so do they need the water of Torah. The Jewish people must never allow three days to pass without a taste of Torah; hence there are Torah readings on Shabbat and twice during the week.