גמ׳ אמר רב חנן בר רבא קלנדא ח' ימים אחר תקופה סטרנורא ח' ימים לפני תקופה וסימנך (תהלים קלט, ה) אחור וקדם צרתני וגו'
ת"ר לפי שראה אדם הראשון יום שמתמעט והולך אמר אוי לי שמא בשביל שסרחתי עולם חשוך בעדי וחוזר לתוהו ובוהו וזו היא מיתה שנקנסה עלי מן השמים עמד וישב ח' ימים בתענית [ובתפלה].
כיון שראה תקופת טבת וראה יום שמאריך והולך אמר מנהגו של עולם הוא הלך ועשה שמונה ימים טובים לשנה האחרת עשאן לאלו ולאלו ימים טובים הוא קבעם לשם שמים והם קבעום לשם עבודת כוכבים
GEMARA: Rav Ḥanan bar Rava says: When are these festivals celebrated? Kalenda, is celebrated during the eight days after the winter solstice, and Saturnalia is celebrated during the eight days before the winter solstice [these holidays were ancient Roman festivals in honor of the god Saturn]. And your mnemonic to remember which festival is that the one that occurs after the solstice is mentioned first in the mishna, and the festival that takes place before the solstice is mentioned after, as in the verse: “You have hemmed me in behind and before, and laid Your Hand upon me” (Psalms 139:5), where the word “before” appears after the term “behind.”
With regard to the dates of these festivals, the Sages taught: When Adam the first man saw that the day was progressively diminishing, as the days become shorter from the autumnal equinox until the winter solstice, he did not yet know that this is a normal phenomenon, and therefore he said: Woe is me; perhaps because I sinned the world is becoming dark around me and will ultimately return to the primordial state of chaos and disorder. And this is the death that was sentenced upon me from Heaven, as it is written: “And to dust shall you return” (Genesis 3:19). He arose and spent eight days in fasting and in prayer.
Once he saw that the season of Tevet, i.e., the winter solstice, had arrived, and saw that the day was progressively lengthening after the solstice, he said: Clearly, the days become shorter and then longer, and this is the order of the world. He went and observed a festival for eight days. Upon the next year, he observed both these eight days on which he had fasted on the previous year, and these eight days of his celebration, as days of festivities. He, Adam, established these festivals for the sake of Heaven, but they, the gentiles of later generations, established them for the sake of idol worship.
