For most of the people there is no today and there is no tomorrow; for them, there is only the past times! Leave your past to live your today and to live your tomorrow!
You have to know accounting. It's the language of practical business life. It was a very useful thing to deliver to civilization. I've heard it came to civilization through Venice which of course was once the great commercial power in the Mediterranean. However, double entry bookkeeping was a hell of an invention.