The “Keseh” Conundrum

There are three Hebrew expressions for the days from Rosh Hashanah through Yom Kippur. Two are well-known: aseret y’mey t’shuvah, “the ten days of penitence,” and ha-yamim ha-nora’im, “the awesome days” or “days of awe.” The third, beyn keseh l’asor, “between keseh and the tenth [of the month of Tishrei],” is used less frequently, perhaps because Jewish tradition has always had its doubts about it.

What is keseh? The word is found in the verse in Psalms 81:4, Tik’u ba’ḥodesh shofar, ba’keseh l’yom ḥageynu, “Blow the shofar on the new moon, on the keseh of our festival.” Assuming that the word, spelled כסה in Hebrew, derives from the verb l’khasot, “to cover,” the early rabbis interpreted it as denoting the “covered” or invisible moon—that is, the period at the end of a lunar month when the sky is moonless. Since Rosh Hashanah, with its blowing of the shofar, is the only Jewish holiday to fall on the first day of a new month, when the moon re-emerges, this verse was taken to refer to it. As Rabbi Naḥman bar Yitzḥak states in the talmudic tractate of Rosh Hashanah: “What is the festival [in Psalms] on which the moon is covered? It can only be Rosh Hashanah.”

But the Talmud fails to take something into account—or at least fails to object to Naḥman’s interpretation. This is that, spelled כסא, keseh appears in one other place in the Bible. This is in chapter 7 of the book of Proverbs, which warns against consorting with wanton women. In it is a description of a young man accosted by such a seductress “late at night, at a time of deep darkness.” “My husband is not home,” she assures him. “He has gone on a long journey, taking his moneybag, and on the day of the keseh he will come home.” Here, keseh is opposed to, and designates a time later than, the darkness of an apparently moonless night. We are either dealing with two homonymous but different words, or with a single word, having variant spellings, that could not have meant “moonlessness.”