Dragons appear in a number of mythological and pseudo-religious stories represented in paintings in the National Gallery. In most instances the beasts symbolise a force of evil. Saint George slays a dragon, and so by implication the forces of righteousness triumph over those of the devil.
A similar theme is followed in the tale of Ruggiero's saving of Angelica in Ariosto's poem 'Orlando Furioso'.
'Dragon's blood' is the name given to the red resin, derived from the Dracaena tree, which was used by artists as an orange glaze for decorating areas of gilding.