In sixteenth-century Spain, the symbolism of light, so closely associated with the concepts of knowledge and spiritual elevation, was embodied in an ambiguous collection of heretical concepts, though not a heresy strictly speaking. Known as alumbradismo, or illuminism, it was condemned and persecuted despite the fact that the ideology espoused by its alleged followers was never rigorously de ned.3 Central to the alumbrados’ religious sensibility, however, was the cultivation of interiority, and this was shared by the famously heterodox theologian and physician Miguel Servet, known in English as Michael Servetus, himself a radical spiritualist of Jewish converso origins4 who spent much of his life in self-imposed exile.