WE moderns araapt to make merry over the gullibility of the Middle Ages, when men believed that certain savage tribes had heads that grew under their shoulders and eyes in the soles of their feet, that the Hand of Glory cast people into an impenetrable slumber, and that somebody would one day find the Philosopher's Stone. But, quite apart from the question of how much truth there may be in some of these strange ideas-and they are doing things now with the atom that make the transmutation of metals seem quite a simple affair-are we ourselves really quite so free from credulity as we make out This is the question that Miss Margaret Radcliffe will debate in the third of her amusing talks this afternoon.