Upon the return of the children of Israel from the Babylonian exile, Ezra the scribe decreed that the people read the Torah on Mondays and Thursdays, the market days, in addition to the Sabbath. A possible reason for this decree is found in the book of Exodus (15:22): “וַיֵּלְכוּ שְׁלֹשֶׁת יָמִים בַּמִּדְבָּר, וְלֹא מָצְאוּ מָיִם” “And they went three days in the wilderness and found no water” The Rabbis interpret water as a metaphor for Torah; thus while wandering in the desert, the children of Israel had become spiritually deprived since they had gone three days without “water” or spiritual nourishment. Ezra thus ordained that no three days were to pass without reading the Torah. When the Torah is read by the appointed reader (Ba`al Koreh), it is customary to use a pointer (Yad). This is done because the law specifically states that the person called up to the Torah must know the exact place of the reading. By using the yad, contact between the impure hand and the holy parchment is minimal and there is less wear and tear.