Question: Why is Torah read on Mondays and Thursdays?
Answer: There are a few different explanations for why the Torah is read on Mondays and Thursdays.
1. Moses went up Mount Sinai to receive the Torah on a Thursday and came back down on a Monday.
2. "And they (the Israelites) traveled three days in the desert without finding water" (Exodus 15:22). The Talmud (Baba Kama 82a) explains that water symbolizes Torah as water sustains the body like Torah sustains the soul. Since the Israelites complained after going three days without Torah, Ezra the Scribe declared that Jews should not go three days without Torah. Hence, the Torah is read every Monday, Thursday and Sabbath.
3. Mondays and Thursdays were market days on which Jews from all over Palestine came to Jerusalem. Ezra the Scribe decided that Torah should be read on these days given the crowds. The market day theory also explains why only part of the Torah portion is read on Mondays and Thursdays while the whole portion is read on Shabbat; Ezra decided on the abbreviated reading so people could get back to their market day business.