Thanks kjj. I looked for the information in the measure that I could. I surely did not go through every topic in the forum but still it wasn't very clear.

So you say people commerce because they thing the value (including expectations of value etc..) is higher? Maybe when people (talking about majorities) buy things they do it for obligation or other reasons, not to get a profit (I get it's not only economical).

Whatever, I don't want to be that 101 tiring post on the recurring topic, I guess I'll have to research a bit more by myself. Thanks anyway.