“Over time, the point where the planet passes closest to the Sun was happening at slightly different points in the orbit.
“For a while, no one knew what to make of that.
“Some astronomers even suggested that there was a hidden planet tugging Mercury around.
“But another astronomer named Simon Newcomb attempted to fix Newton’s law by tweaking it.
“Sure, it helped solve the problem with Mercury, but it didn’t address why Newton’s law broke down.”
But, Einstein came along and discovered where the problem was.