Although Gilbert achieved success as a humorist, he always wanted to be a moralist. His failure to be taken seriously as a social philosopher, and in particular his failure to develop the one philosophical concept that he formulated clearly—the very un-Victorian idea that causality is operative even in the sphere of morals—are traced by Brenner to specific disturbances in his oedipal and pre-oedipal development. Recurrent themes in his plays and in the Bab Ballads, notably those of the changeling, the multiple personality, cannibalism, and the malice towards older women, combined with obvious anal-sadistic character traits and an excessively paternal attitude towards younger women, point to an unresolved conflict centred round the birth