The idea hit me in early 1977, during of all things a pistol match. And the ratio that first came to mind that weekend morning still seems about right. It is a rule — okay, a “guideline” as we now like to say — that explains and to a limited extent influences much of our daily lives. That morning I named it the 20 percent rule. In the — Lord help me — nearly 50 years since that day it has held up pretty well.
Much has been written in the last 75 years about how the U.S. gained an edge in the Pacific in World War II when the Japanese code was broken. In recent weeks it turns out I may have been trying to recreate that feat, and have begun to understand the challenges those skilled codebreakers faced.