"Etymologies are either obvious or wrong"

[Ronald E.Emmerick]

"Etymologies are either obvious or wrong". This is a saying I first
heard from my former teacher in Cambridge, the late Sir Harold Bailey,
who also knew its source. I made a note of it but cannot find it. I
thought it was an American linguist but I am not sure. It has been
suggested it may be Meillet, but no one has so far been able to give me
chapter and verse. It is not in the OED.

--
Prof. Dr. Ronald E. Emmerick
Hamburg University