On September 11th, 1789, France's newly formed National Assembly gathered to vote on whether King Louis XVI should retain veto power over its laws. The way lawmakers arranged themselves in the chamber that day would echo through the next two and a half centuries of democratic politics. Those who wanted to preserve royal authority sat on the king's right; those who opposed him occupied the left. It was a practical seating choice driven by the architecture of the moment, not ideology. Yet this single day's arrangement hardened into a conceptual framework so durable that we still sort politicians left and right today, often without knowing why the categories exist at all. The metaphor outlasted the monarchy, became standardized across parliaments worldwide, and eventually calcified into a spectrum so familiar that it feels inevitable rather than accidental. What began as a physical arrangement in one room became the language through which democracies would argue about themselves for generations.