tetraktysThe sum 1 + 2 + 3 + 4 (the fourth triangular number), held in reverence by the Pythagoreans (see Pythagoras). The tetraktys, or "holyfourfoldness," was taken to represent the four classical elements: earth, air, fire, and water. Related categories HISTORY OF MATHEMATICS TYPES OF NUMBERS Also on this site: Encyclopedia of Alternative Energy & Sustainable Living Encyclopedia of History |