The Halcyon is a bird of Greek legend and the name is now commonly given to the European Kingfisher. The ancients believed that the bird made a floating nest in the Aegean Sea and had the power to calm the waves while brooding her eggs. Fourteen days of calm weather were to be expected when the Halcyon was nesting - around the winter solstice, usually 21st or 22nd of December. The Halcyon days are generally regarded as beginning on the 14th or 15th of December.
Katrina sent me this info as a way to help me think about doing nothing as a positive thing, adding that she loves watching the kingfishers in Maine. I'm not sure what they look like there, the one on the R or the L?
I hate to admit that I'm more apt to think of the Horse Latitudes when thinking of doing nothing. Tossing the horses overboard when there's no wind in your sails . . . Not to sound too depressing!