"The court jester is a universal phenomenon. He crops up in every court worth its salt in medieval and Renaissance Europe, in China, India, Japan, Russia, America and Africa."
The book Fools Are Everywhere: The Court Jester Around the World by Beatrice K. Otto is available from Amazon.
>Fools and Jesters at the English Court by John Southworth is a reign-by reign account of court fools from their origins in Carolingian Europe and Celtic Ireland to the time of James I. It is also available at Amazon.