An attempt is made to study the nature of Swinburne's relationship with Mary Gordon, his cousin, who appears in many of his love poems. The author is particularly concerned with the question of whether or not Mary Gordon shared Swinburne's interest in flagellation. His procedure is to make as many inferences as possible from Mary Gordon's novels in which flagellation figures as a prominent theme, as well as from what is now known of Swinburne's own erotic activities. He draws several conclusions: 1, that Mary probably did know about her cousin's flagellant activities during his childhood and youth; 2, that Mary's own masochistic and sadistic fantasies were projected into her