Tufte: Envisioning Information: "Layering and Separation"
by Carson Reynolds
Layering and Separation covers methods for increasing the dimensionality of flatland by layering information on top of other information. The “separation” bit comes in with methods to help distinguish one layer from the next. The laundry list includes: color annotations, different density of type (toned down grids), gestalt-like interactions between white and black, spacing issues.
Tufte closes with a quote from Kepes, quoting Lao Tse in turn:
“A vessel is useful only through its emptiness. It is space opened in a wall that serves as a window. Thus it is the nonexistent in things which makes them serviceable.” -Lao Tse