Laws of Media By Eric & Marshall McLuhan
The McLuhans suggest (rightly, in my view) that every artifact or medium does four things: It enables something new, it obsoletes something, it rekindles something from the past, and it sets the stage for its own reversal to something new when pushed to the limit. If we understand each of these four attributes (or laws of media) we have a tool that can be applied to the development of our understanding of any new technology we encounter.