A more than half-length depiction of the saint, standing in front of a skull and contemplating the angel who shows him a glass recipient filled with transparent water, alluding to the purity that anyone aspiring to the priesthood should possess. In his humility, the saint thinks he will never reach such perfection and renounces the calling. In keeping with the mentality of the Counterreformation, this subject was widespread during the seventeenth century.

The skull and whip on a stone also allude to penitence and humility, as does the saint's serge clothing.

This is a work from the artist's mature period. Echoes of tenebrism are still discernible, with strongly illuminated figures emerging from the darkness, and a careful rendering of the tactile qualities of the objects.