It's true, although it's still useful in many instances if we take a more general approach. So, let's say that instead of focusing on the effects of discoverin

It's true, although it's still useful in many instances if we take a more general approach. So, let's say that instead of focusing on the effects of discovering oil on the national budget, we could focus on studying the economics of natural resources in a more general sense. Here historical evidence could be perfectly useful.