Study Rosh Hashanah folio 20B with parallel Hebrew-English text, traditional commentary, and modern study tools. Free access to Babylonian Talmud online.
Text Excerpt
האי מיחזי כשקרא, האי לא מיחזי כשקרא.
In this case, where the witnesses withhold testimony about what they saw and Rosh Chodesh is pushed off to the next day, it looks like a lie, as the moon might have been seen by others as well, and people will wonder why Rosh Chodesh was not sanctified the previous day. In that case, where the witnesses testify about something that they did not see and Rosh Chodesh is a day early, it does not look like a lie, as everybody knows that it is possible that only a few people saw Rosh Chodesh.
אמר שמואל: יכילנא לתקוני לכולה גולה.
§ Shmuel said: I am able to fix the calendar for the entire Diaspora without witnesses. Shmuel was an expert on the movement of the celestial bodies and on the principles governing leap years and additional days added to months.
אמר ליה אבא אבוה דרבי שמלאי לשמואל: ידע מר האי מילתא דתניא בסוד העיבור: נולד קודם חצות או נולד אחר חצות? אמר ליה: לא. אמר ליה: מדהא לא ידע מר — איכא מילי אחרנייתא דלא ידע מר.
Abba, the father of R' Simlai, said to Shmuel: Does the Master know the meaning of this statement, as it is taught in a baraita dealing with the secret of addition, which discusses calendric calculations: Differentiate between when the molad occurred before midday and when the molad occurred after midday? He said to him: No, I do not know what this means. He said to him: Since the Master does not know this, there are probably other matters that the Master does not know, and therefore you must not establish a calendar, relying upon calculations that were made based on faulty or insufficient knowledge.
כי סליק רבי זירא, שלח להו: צריך שיהא לילה ויום מן החדש.
As for the meaning of this obscure baraita, when R' Zeira went up from Babylonia to Eretz Yisrael, he sent back a letter to his colleagues in Babylonia: In order for a day to be sanctified as Rosh Chodesh, it is necessary that both the night and the day be of the new month. That is to say, the molad must occur before the beginning of the night.