The analogy to time. Not long ago the world took exactly 24 hours to spin on its axis. The time it took to spin was always exactly, to the millisecond, 24 hours, not because the amount of time it took the world to spin was precisely equal every day (it has never been) because the day was defined by the spin and divided into 24 equal units of one hour. Variations were too minute for the technology of the day to perceive. The world spun on and on. Technology climbed steady up the hill of precision. A day came--we could name it, but I don't know its name--when the technology of the ruler exceeded the standard. There was a great divorce. Time became the standard by which the rotation of the earth was measured: the rotation no longer measured time. Slave became master then. The clock on which the ants live measured too erratically to be of use. Time measures only itself. It is without object or referrent--unless, at a moment, for a reason, someone chooses, temporarily, to give it one.
Words effected the same divorce, and at approximately the same time.