I like the explanation part. But I think the "fixed over time" is not that exact. It is a little bit confusing. What do you mean by behavior and characteristics are fixed over time? Besides that, I really like your definition. --Hetong Li
I think the explanation is pretty clear. It's a direct quote from Oppenheim Wilsky, so it probably should be. Next time you should probably cite your source. The answer is correct. Good work. --Ben Moeller
