I home-schooled myself for a year and stumbled upon them, and decided to call them "differentials" because I had heard that term before. It's also possible I wa

I home-schooled myself for a year and stumbled upon them, and decided to call them "differentials" because I had heard that term before. It's also possible I was had been sitting too close to my brother while he was studying them and had forgotten about it for a time.