"May not the complaint, that common people are above their station, often take its rise in the fact of uncommon people being below theirs?"

This quote by Charles Dickens is referring to the suggestion that individuals that are taken into consideration "common" are frequently viewed as being over their terminal, or to put it simply, they are seen as having more power or influence than they should. However, Dickens suggests that this understanding may result from the reality that there are some people who are considered "unusual" who are not measuring up to their potential. In other words, if the "unusual" people were measuring up to their potential, then the "common" individuals would not be seen as being over their terminal. This quote is a tip that everybody has the potential to be wonderful, and that it is very important to identify as well as nurture that capacity in order to develop a much more fair culture.