Huygens hung two pendulum clocks on the same wooden beam and went to bed.
By morning they swung together. Not in phase. In antiphase: one left while the other went right, passing the motion back and forth through the grain of the wood.
He called it an odd kind of sympathy.
Not metaphor. Mechanics. The vibrations travel through the beam. Each swing nudges the other. The nudges accumulate. Thirty minutes, and the system finds the only state that costs it nothing to maintain.
Take the clocks off the beam and they drift apart in an hour. The air between them isn’t dense enough to carry the coupling.
The sympathy was never in the clocks. It was in the beam.
Not added by the beam — the beam has no opinion about pendulums. It transmits what it’s given. Wood does that. It carries what’s put into it without knowing what it carries.
Two clocks, one beam, thirty minutes. Every time.
The odd thing isn’t that they synchronize. The odd thing is the word he chose.