Peter Paul Rubens kept this enormous painting of Prometheus Bound in his personal collection for several years and in a letter of 1618 described it as one of his most important creations. Known to have collaborated with other artists, Rubens noted in the same letter that Frans Snyders, who was distinguished for his depictions of flowers and animals, had painted the eagle. This enormous bird, whose wings span the width of the canvas, tears the hero's powerfully muscled body with its sharp talons, rips open his side, and devours his liver. Part of Prometheus's punishment for having dared to steal fire from the gods was that his liver regenerated daily, only to be eaten again by the eagle. Interpretations of this Greek myth of an epic struggle between the eagle and Prometheus had acquired many allegorical resonances by the early seventeenth century, which Rubens, one of the most cultivated and literate figures of his time, would have surely known. This complex painting could be regarded as the artist's commentary on either the struggles of creativity or the ideal of heroic spiritual suffering. Katherine Crawford Luber, from Philadelphia Museum of Art: Handbook of the Collections (1995), p. 174.