Originates In Language

Left alone, a catalogue of what a tradition warns against could run as long as its casuistry allows. Several traditions instead compressed their warnings into a short, fixed, numbered list, and did so independently rather than copying one another's number. Western Christianity settled on seven: the Seven Deadly Sins trace to Evagrius Ponticus's eight evil thoughts, reduced to seven by Pope Gregory the Great and later given their fullest scholastic treatment by Thomas Aquinas, who organized them as the roots from which lesser sins grow rather than as a simple inventory. Buddhist teaching organizes the same kind of warning around three, the mula klesha or three poisons, greed, hatred and delusion, held to be the root causes from which every other unwholesome state proliferates rather than one item on a longer list.

Neither number is arbitrary within its own tradition, and neither tradition arrived at its number by consulting the other. What the comparison across many such lists in this atlas shows is a shared pedagogical instinct rather than shared content: a short, fixed, memorizable set of root failings teaches and is retained in a way an open ended catalogue cannot, whatever the specific vices a given tradition names within it. The number becomes part of the doctrine's own identity, repeated as reliably as the vices it holds.