Why did the Babylonian exile last only 70 years, while we have been in the present exile for nearly 2,000 years?

We can gain a perspective on this question by comparing the respective wrongs that had to be corrected by the two periods of exile.

There is a statement of our sages that compares "the earlier people" (i.e., those of the period of the First Holy Temple) with "the latter people" (i.e., those of the period of the Second Temple): "Because the sin of the earlier people was revealed, the end [of their exile] was revealed; because the sin of the latter people was not revealed, the end [of their exile] has not been revealed."

This we can understand as follows. In the period of the First Temple, when the transgressions of our people involved visibly outright evil (i.e., "their sin was revealed"), they repented of them at once, and their exile came to an end within a short time (i.e., "the end [of their exile] was revealed"). In the period of the Second Temple, by contrast, the prevalent sin was baseless hatred. In such a case people can delude themselves that this is not really a sin, for they can persuade themselves that their hatred of their fellows is justifiable. That is to say, "their sin was not revealed" even to themselves. And for this reason "the end [of this exile] has not been revealed," for people do not genuinely regret having sinned in this way.

Another possible explanation for the length of the current exile: It takes longer to sift and elevate subtle traces of evil than to sift and elevate coarse manifestations of evil, which are immediately identifiable.