The general idea is that the value of something comes from the amount of human work that went into it, more or less. If you build paper planes and I buy one fro

The general idea is that the value of something comes from the amount of human work that went into it, more or less. If you build paper planes and I buy one from you it's because I value the work you put into it (and, transitively, the work put into the paper it was made of etc...). If I think I can do it better, or that I can find somebody else who does it for cheaper, then I don't buy your product. When I pay my rent, what work do I reward? What added value does the land owner offer to society? What service do they provide?