וַיֵּט משֶׁה אֶׁת־מַטֵּהוּ עַל־הַשָּׁמַיִם...
And Moshe stretched forth his staff heavenward...(Shemos 9:23)
“Rabbi Yehuda said: the staff of Moshe weighed 40 se’ah. It was made out of sapphire, and the ten plagues were engraved on it.” [Midrash Shemos Rabba 8:3] Rabbi Yehuda is most likely referring to the weight of water which occupies a space whose volume is 40 se’ah.
(If we do the math, we find that Moshe’s staff weighed 750 pounds: 40 se’ah is about 340 liters. A liter of water weighs 1 kilogram. Since each kilogram is 2.2 pounds, 340 liters of water weigh 750 pounds.)
Based on the fact that a kosher mikveh needs to have at least 40 se’ah of water in it, why do you think the weight of Moshe’s staff needed to have a weight of 40 se’ah?
Based on the commentary of Imrei Yosher on the Midrash, the explanation is as follows: The number 40 is associated with the concept of transformation. For example, inside a mikveh (that must measure 40 se’ah), an impure person is transformed into a pure one. Moshe’s staff was needed to make a transformation of the physical reality in Egypt.
Can you find other things in the Torah that have the number 40 and are connected to the concept of transformation?
