St James is depicted on the right-hand side with his attributes (staff, cap with shell) watching manuscripts being devoured by fire in a bonfire on the ground in front of him. On the opposite side, the magician Hermogenes, whose face is outlined very realistically, is flanked by two demons. Above, against a background of black clouds that contrast with the pale blue of the sky, we see the "dance of the howling devils" who flee in the face of Santiago's victory, mentioned in the Flos Sanctorum and which was probably the source of inspiration for this work.
In the centre of the composition, in the foreground, are the books thrown into the flames by Hermogenes as a sign of abandonment of his ancient wisdom and conversion to Christianity.