Every July 27th, in a quiet corner of downtown Madrid, a phenomenon takes place that has puzzled both the faithful and the curious for centuries: a small vial containing what is considered the blood of Saint Pantaleon seems to inexplicably change from a solid (coagulated) to a liquid state. This phenomenon occurs at the Monastery of the Incarnation and, for generations, many have interpreted it as a miracle. At the same time, it has sparked the interest of scientists and heritage scholars.