Education, I think, and education in the sense of moral understanding more than that of playing the piano or drawing. I've made a post on Austenations with some quotes from JA's other novels that talk about an improved mind - link below.

I think this can then be separated from excellent understanding in the sense that the excellent understanding is something like what we would know as IQ, and the improved mind is the education on top of the underlying IQ. A good structure of factual knowledge is at least as important as underlying intelligence - there is a long tendency of very smart people to make very stupid statements when talking about an area they don't know very much about. Critical thinking by itself doesn't get people very far. If it did scientists would not need to do all those experiments.