Location from Foundation by Isaac Asimov
The Milky Way — twenty-five million inhabited worlds, a trillion-year-old civilization in decline, and the stage on which Hari Seldon played the longest game in human history.
Twenty-five million worlds. That number is the foundation of psychohistory — a population so vast that individual behavior washes out and statistical patterns emerge with mathematical certainty. The galaxy in Seldon's time was a single political entity that had forgotten it could be anything else. The Galactic Empire had ruled for twelve thousand years, long enough that most citizens assumed it was a natural law rather than a human institution. The fall, when it came, was so gradual that most people living through it didn't notice. Provinces stopped sending taxes. Communication delays grew longer. Trade routes became dangerous. Technology was maintained but no longer understood — the difference between a civilization that builds and one that merely uses. The barbarian kingdoms that replaced Imperial authority on the Periphery weren't invaders but locals who simply stopped pretending the Empire existed. Seldon saw all of this in his equations. Thirty thousand years of darkness — feudal wars, lost technology, billions dead from preventable causes — unless someone intervened. Not to stop the fall, which was impossible, but to shorten the interregnum. One thousand years instead of thirty thousand. That was the plan. That was the Foundation.
A spiral galaxy seen from without: silver-white arms curving outward from a dense golden core, dark dust lanes threading between the arms, individual stars invisible at this scale but their collective light painting a structure of staggering beauty. The inhabited worlds cluster along the spiral arms and concentrate toward the center, with the Periphery — Terminus's neighborhood — a sparse scattering of stars at the galaxy's edge. The galaxy is the map on which the Seldon Plan is drawn, each crisis a pin, each trade route a thread, the whole thing a single organism too large to see from inside.
Also known as: the Milky Way, the Empire, the Galactic Empire, the galaxy