Is ignorance never ending?

In class when we discussed the three different types of ignorance I found it enlightening. I had always thought that all ignorance was the same. The idea that there is a progression from double ignorance to simple ignorance to virtuous ignorance and that one's own ignorance can improve to another state is baffling. If this is true than I suppose we can never escape a state of ignorance. Once we reach a state of virtuous ignorance can we improve from there? Do we go to a state of knowing or are we always ignorant? Is complete knowlege on a particular subject ever attainable?