To pour oil on troubled waters, as a figure of speech, means to soothe the troubled spirit. “A soft answer turneth away wrath.”
As a physical fact, Professor Horsford, by emptying a vial of oil upon the sea in a stiff breeze, did actually still the ruffled surface. Commodore Wilkes, of the United States, saw the same effect produced in a violent storm off the Cape of Good Hope, by oil leaking from a whale-ship.
Origin of the phrase: The phrase is mentioned by the Venerable Bede in his Ecelesiastical History written in Latin, and completed in 735. Stapleton translated the book in 1565. St. Aidan, it appears, gave his blessing to a young priest who was to set out by land, but return by water, to convoy a young maiden destined for the bride of King Oswin or Oswy. St. Aidan gave the young man a cruse of oil to pour on the sea if the waves became stormy. A storm did arise, and the young priest, pouring oil on the waves, did actually reduce them to a calm. Bede says he had the story from “a most creditable man in Holy Orders.”
St. Aidan died in 694, and Bede died in 735. There is no question in archaeology so often asked to be explained as this.