Ancient wisdom often sounds like common sense now that it is commomly taught. What is some ancient wisdom that we no longer teach because it was wrong?
Drill a hole in your head as a cureall for any mental behaviour abnormalities. Still practised as an emergency surgery, only to release life-threatening blood and pressure buildup inside the cranial cavity.
Fun fact: This is also how Ethernet (wired network connection) got its name. Ether was already dismissed as a theory, but "omnipresent, completely-passive medium for the propagation of electromagnetic waves" was a good description of hardware layer that can transfer data in a way that's abstracting all the signal handling complexity for higher layers.
So in a way I'm actually sending this comment via Ethernet.
Interestingly, we've kind of looped all the way around. We describe the particles of the universe with omnipresent fields, which isn't really the same idea as aether but has some neat similarities.