The first commandment given to the Jews as a nation was that of sanctifying the new month. (We will hopefully deal with the nature of this commandment in another issue.) The Ramban, in his explanation on the Torah (Shmos 12:2), speaks about the very issue we are concerned with: the names of the months. He starts by explaining that the Talmud Yerushalmi (Rosh HaShana 1:2) tells us where these names of the months came from: "The names of the months came up with us from Babylon." The Ramban notes that as we notice in the Chumash, at first, the Jewish people had no names for the months. The reason for the adoption of the names of the months when our ancestors returned from Bavel to build the Second Temple stems from the fact that at first, the reckoning of the months was a memorial to the exodus from Egypt. Nissan was the first month from (the anniversary of) our exodus, and so on. However, when the nation of Israel returned from exile in Bavel, the words found in Yirmiya (16:14-15) came true: "Behold, days are coming when it shall no more be said "As The Lord lives, that brought up the children out of the land of Egypt, but: As The Lord lives, that brought up and led the children of Isreal from the land of the North, and from all the lands into which he had driven them."

After that time, we began to call the months by the names that they were called in the land of Bavel. We are thus reminded each time we mention the name of a month that we were in exile in Bavel, and from there Hashem redeemed us and brought us up to our the land of Israel. Hence, through the names of the months we remember our second redemption just as we had done with regard to the first one.

Yet, just because the names have changed, that does not mean that we no longer remember the exodus from Egypt from the month names. In fact, when one looks at the times in the Torah where these Babylonian names are used, it is usually in the following way: "The first month, the month of Nissan." We have a reminder through the names of the months of both exiles that we, through the gracious hand of G-d, were redeemed from.