Tetrad or 4 laws of media

Paul Levinson argues that the "tetrad" is the key to understanding any medium and its impact. The tetrad consists of four questions:

1. What does a medium enhance or amplify?
2. What does a medium obsolesce or push out of prominence?
3. What does a medium retrieve from the past?
4. What does a medium reverse or flip into which it reaches the limits of its potential?