
Could we have done our analysis using equations instead of diagrams?
You bet. Equations are especially useful if the problem is more complex because adding variables is a lot easier than adding dimensions to the chalkboard. Plus, it is helpful to use numerical estimates of the slopes.

The technology for using M, G, and T to control the economy is similar to the technology for using thruster rockets to control a spacecraft. In the 1960's we learned to land a rocket on the moon (or the other side of the Earth).

Unfortunately, economists' effort to "fine tune" the economy were somewhat less successful than the NASA missions.
