So what do the communication technologies of the past tell us about the social media of the future? Why are Hiltz and Turoff looking at the cost of computer-mediated communication compared to the telephone? After all, isn't that a tactical issue rather than strategic? It turns out that it's not. History teaches us that when you reduce the cost of sharing information, you can have profound effects on a society's literacy rates and on who is allowed to control what kinds of information can be distributed in a social system. Let's briefly consider what happened when Gutenburg's printing press reduced the cost of publishing books and then consider what lessons this has for social networks.