Impairment in the ego function of speech and in verbal expression of abstract thought in patients with otherwise high intellectual endowment is observed in a wide category of mental disorders. These run the gamut from word inhibition to inability to think abstractly. Analyses of three male patients revealed such impairments to be both a defense and a gratification of regressive infantile wishes belonging to the undifferentiated stage of libido development when a sense of fusion with the mother is paramount. The mothers of these patients were either psychotic or borderline cases who seductively exhibited their nakedness to their sons; denial of the mother's castrated state became essential and the son chose the defense of fusion with her. Failure properly to