In Reply to: Put on my thinking cap posted by Gary Martin on November 22, 2008 at 08:59:
: : Can anyone confirm the widely held belief that the origin of the phrase "put on my thinking cap" comes from an Oxford University undergraduate common room where the fellows would sit and mull over some problem and were constantly having their train of thought interrupted, so they devised the simple rule that if one were sitting ruminating with a cap on, then they were not to be disturbed. The caps used became known as thinking caps - thus was the phrase born.
: That's a possibility, although I can't find any evidence to support it. If Oxford students did wear such caps they would have been under the name of 'considering cap', rather than 'thinking cap. See:
I don't know about Oxford scholars, but British Guards officers traditionally wear their caps at breakfast if they don't wish to be spoken to. (Though it's not assumed that they are thinking very much, unless along the lines of "That last bottle of port was a mistake.")
But 18th-century gentlemen did routinely wear caps to think. They shaved off their own hair, and wore wigs with formal dress. When reading or writing at home in his study or library a man wouldn't wear his wig, but to keep his shaven head from the cold he would wear a soft cap, often of velvet or fur. There was a clear association of caps with intellectual activity; whereas a statesman or aristocrat would have his portrait painted in formal dress, it was an accepted convention for scholars, philosophers and artists to be painted in caps and dressing-gowns. E.g.
Jean-Jacques Rousseau: http://www.nationalgalleries.org/collection/online_az/4:322/result/0/5337?artistId=6240&artistName=Allan%20Ramsay&initial=R&submit=1