What can you say about struggling hard to learn a Mathematics course while you are "young", not succeeding, but learning the same course effectively, later, when you are "not as young"? Meanwhile, you studied other Mathematics courses with acceptable success, but NOT that particular one with which you struggled at the time that you were "young". ASSUME that the teaching quality was the same for all courses and that the course content of that particular course was the same both when you were "young" and when "not as young". What could account for this? Increased brain growth? Increased study skills? Increased subject-matter development? What --- anything els?