(this post is cross-posted at Torah Thoughts and at DafNotes)
We recently learned in daf yomi the calculations, and miscalculations, of the 70 years of exile after the destruction of the first Beis Hamikdash and prior to the rebuilding of the second Beis Hamikdash.
One would think that 70 years is not too difficult to keep track of, especially when you are living within the thick of it. However, we see Ahashverosh miscounted the 70 years. So did other people. Nobody knew from when to begin the count of 70, therefore everybody's count was skewed and nobody had the correct target date. It was only after the rebuilding of the Beis Hamikdash began that we could look back and say we know when the count of 70 years of exile began.
The same is true in the upcoming parsha regarding the creation of the golden calf. The Jews knew Moshe was going to be on Mt. Sinai for 40 days. How hard is it to count 40 days? Yet they miscounted and that led them to making the mistake of creating the golden calf.
We have many dates and calculations throughout tanach and Jewish history. Great Rabbis have calculated with varying conclusions the dates of the coming of Moshiah, the end of the world, the redemption, etc. These dates come and go. We then question how the great Rabbis could be wrong and lose faith (sometimes) or simply become cynical when hearing such things. We have to realize that we never know where to begin the count, and therefore our counts and calculations are always wrong. It is only in hindsight we can look back and say where the count began.
The gemara says the world will only last 6000 years. That is pretty good reason to start getting nervous. We are now in the year 5767 (of the Jewish calendar). That only leaves 233 years left to go before armageddon!
But considering the fact that pretty much every count in the Torah and Jewish history was found to be miscalculated, we have to consider that we have no idea when the count of 6000 years begins. Did the 6000 years begin from the first day of creation? Maybe from Avraham recognizing monotheism? Maybe from matan Torah? Maybe from the jewish nation entering Eretz Yisroel? Or maybe from multitudes of other placemarks in jewish history. We have no idea when the count begins, and will only know after it actually happens.
I think it was the Rambam who said not to bother calculating the coming of the mashiah, as doing so only causes people to lose faith when the predicted event does not happen. Instead of worrying about specific dates and calculations that will almost definitely be wrong anyways, we should heed the advice of the great masters and be "mefashfesh b'maasav" - look at our ways and correct our actions and try to prepare in that way for the days of Mashiah.