The most widely recognised icon in the world is the human heart, as depicted, for example, on playing cards. But a heart has neither a dent nor fold in its base, it is not 'nipped in the waist' and it does not have a sharp point on its underside. Since the days of the ancient Greeks, anatomists have correctly reported that the heart is shaped like a pine cone or has the outline of an upturned pyramid. Why is the shape of such a popular icon so at variance with the heart's true form? It seems that the indentation or fold in the base of the heart first appeared in Northern Italy in the early years of the fourteenth century. It was the result of an error originally made in an anatomical text by Aristotle. In the sixteenth century, anatomists finally corrected the error, but, by that time, the scalloped heart icon had become so established in the visual arts that it could no longer be changed. This work also contains a section devoted to a cave, shaped like the interior of the heart, in an allegorical print by Jan Saenredarn (1604). The representation was a creation of Hendrik Spiegel (1549-1612), one of the fathers of Dutch grammar and a friend of Cornelis Cornelisz, Hendrik Goltzius and Karel van Mander.