“Great authors are admirable in this respect: in every generation they make for disagreement. Through them we become aware of our differences.”

I don't think it is just the great authors (or even just authors) who do this. Nor do I believe that it takes making disagreement to make people aware of their differences. I suspect most are already quite aware of differences, and the real gift is to make others aware of the complexities and possibilities of the elements of truth in such differences...