The Ancient Greeks seemed to believe that just about everything was made out of four of something else. For instance, the physical world was thought to be composed of earth, wind, water, and fire; for the human body the four humours were blood, black bile, yellow bile, and phlegm. Tidy model. What are an identitifier's 'humours'? How about linkability, discoverability, uniquenessability, and memorability? In On the Nature of Man , Hippocrates wrote that health is primarily that state in which the Read More...