Why does Rashi go to such lengths?
hitalalti (Exod. 10:2) Rashi writes:
I mocked, like ki hitalalt bi (Num. 22:29) ('for you mocked me'), halo ka'asher hitalel bahem (1 Sam. 6:6) ('see when he mocked them') referring to Egypt. It is not an expression of doing and action, for if that were the intention it should have written olalti ('I did') like ve'olal lamo ka'asher olalta bi (Lam. 1:22) ('and do to them as you have done to me') asher olal li (Lam. 1:12) ('which he has done to me').Usually Rashi, who is known for the brevity of his comments, makes his point without negating another possible interpretation. Why does he change his approach here? It would seem that this is because the other interpretation is the opinion of Onkelos whom Rashi often follows. As he disagrees with Onkelos here he feels obliged to explain his reasons why. This is a common practice among the Rishonim: when they are aware that their opinion is at variance with another they explain themselves at greater length.
The names of the units of time: 'month' and 'year'
hachodesh hashana (Exod. 12:2) ('the month the year') The Hebrew calendar 'is the first mitzvah that Israel was commanded' (Rashi, Gen. 1:1). What is the significance of the names chodesh and shana? R' A. ibn Ezra explains:
The year is purely of the sun. It proceeds on its cyclic course for 365 days and close to Ό of a day till it returns a second (shenit) time and for this reason it is called a year (shana). Similarly the moon has no year at all [he explained previously that the moon does not return to its original position] just as the sun has no months, for nothing is renewed in the sun, the only renewal (chidush) is in the light of the moon and this is why it is called month (chodesh). [n.b. in English the words 'month and 'moon' are also related] Having established these notions he compares the calendars of the Christians and the Moslems with the Hebrew calendar. He argues that the month of the Christian calendar which divided the year into 12 units (each being roughly equivalent to a lunar month) is based on human conventions and is unrelated to the month which has its base in nature (i.e. the lunar month). Similarly the Moslem year which is simply 12 lunar months is 11 days short of a natural (solar) year hence 34 Moslem years are equivalent to 33 solar years.