How do you determine the value of a piece of art?

How do you determine how valuable a piece of art is actually worth? How much can a single painting actually mean? Before typing up this blog I watched a video from the University of Manitoba that somewhat answered these questions. He took the idea of two paintings, one being 300 years old. Some people would say the older one is more valuable, that they'd prefer to see that one over the copy. I think that in a way, that is true. Considering all the artistic properties that the copy doesn't have, such as riginality, the copy will never be able to accumlate the same properties simply because it is just a copy. Yes, newer is nice and it's refreshing, but new also can be taking what has already been done and recreating it just so it's more "in the now." The idea has already been used in the past so why? Why try to recreate something already so valuable? An older piece of art WOULD be more valuable, I believe, because it was more of a truth to it. There's a lot more meaning to an original than a copy because it made more sense to what the time period was, what the artist was about, and the culture that surrounded them. A copy has no story except that it's a copy.