The reference to being 'As Mad as a March Hare' first appeared in Chaucer's Friar's Tale in the 14th century.
"The March Hare will be much the most interesting, and perhaps as this is May it won't be raving mad -- at least not so mad as it was in March!"
I love this depiction of the Mad March Hare by Natasha Wescoat.. I checked out her website after finding this picture online, and she has some very unusual, bright, whimsical paintings.. very modern, yet very cute and traditional at the same time.
.. when the hares box as part of their courtship ritual – the 'boxing' is actually females battling off unwanted advances from the males.