Harvey vs Galen: does blood flow in circles or ebb like tides?

Galen, I counted the heart's every beat and measured the blood it moves—no liver could brew that flood anew each hour; the blood travels in a circle.

Bold arithmetic, young man, but I dissected apes and gladiators while Rome watched; the liver makes blood, the body consumes it like oil in a lamp.

Then explain the valves in your veins that let blood pass one way only—nature built no one-way doors for a tide that ebbs both directions.

You trust your little valves; I ruled medicine for a thousand years—show me the invisible passages your circle demands, and only then bury me.

The microscope found them after we both were gone, Galen—your reign ended not because I shouted louder, but because the blood kept moving in circles, exactly as I said.