I mocked animal magnetism back here. But if it hadn't been for Franz Mesmer and mesmerism, Michael Faraday wouldn't have tried to debunk its resurgence. Because Faraday discovered so many properties of electricity and magnetism, James Clerk Maxwell felt compelled to describe electromagnetism mathematically. Maxwell inspired everybody and led indirectly to a host of predictions and experiments including those by a young Dutchman named Pieter Zeeman who surreptitiously conducted experiments for which he was fired (he later won the Nobel Prize for those experiments). Zeeman's work inspired Johannes Stark's work which in turn inspired Wolfgang Pauli, who in turn inspired Isidor Rabi to propose that certain atomic nuclei should resonate with radio waves when placed in a magnetic field. This idea led to the development of nuclear magnetic resonance (NMR) after the Second World War by Felix Bloch and Edward Purcell. NMR led directly to magnetic resonance imaging (MRI).
So the basic truth of what Mesmer tried to do--to heal people with magnets--turned into healing people with the help of magnets.