Musar for Chullin 120:2

We know that the sun and moon had originally been created equal in size and power (compare Genesis 1,16, את שני המאורות הגדולים, i.e. the two great lights). The Talmud, חולין 60 describes that the moon argued with G–d that two kings cannot reign simultaneously, and was told to diminish its size. Whereas the Talmud, of course, refers to the physical sun and moon, the ones we can see, the story mirrors a corresponding dichotomy in the higher Celestial Regions.

Since we are already on the subject of the relative importance of the sun and the moon, I will now proceed to explain the discussion in Chulin 60b described as having taken place between the moon and G–d. So many commentators, and especially Kabbalists, have written on this subject that all I want to do is deal with it on the most fundamental basis, i.e. the פשט. I believe that the sun and moon in the story are to be accepted at face value; they may, however, be symbols of the relationship between study and performance at the same time. Just as the moon depends on the sun, so performance depends on the knowledge of what is to be performed, when it is to be performed, and where it is to be performed. The wording of the statement of Rabbi Shimon ben Pezzi in the Talmud illustrates this point. The Rabbi questioned the verse in Genesis 1,16 according to which G–d made "two large luminaries, the great luminary to dominate by day and the small luminary to dominate by night." In order to deal with the apparent contradiction of there being two great luminaries, the Rabbi tells us a parable in which the moon complained to G–d about two kings not being able to wear one single crown (to rule simultaneously). G–d thereupon invited the moon to reduce itself in size. The moon replied that it could not see why it should be punished for having made a valid observation. Thereupon G–d told the moon to dominate (shine) by day as well as by night. To this the moon replied that there was no point in shining by day since its light would not be noticed (after the sun already shone by day). G–d then consoled the moon by telling it that in the future Israel would base its calendar on the lunar cycles. The moon responded that Israel would not count its days according to the lunar cycles because the Torah already stated in Genesis 1,14 that the luminaries would determine the seasons, i.e. solstices. G–d then told the moon that the righteous, i.e. Jacob would share its adjective "small" also with Samuel and David, all of whom would be called "small" in the Bible, (cf. Amos 7,5, and Samuel I 17). When G–d realized that the moon was still not satisfied He told the Jewish people to offer a sin-offering on His behalf on every New Moon in order to expiate for His having reduced the moon in size.