In this pioneering work, Bion’s revolutionary modification of the psychoanalytic model of the mind: his theories of  thinking, affects, and groups find  applications which illuminate and integrate the author’s previous study of Bion in The Kleinian Development. In these studies, which range from protomental states and reversal of alpha-function, through family patterns, to problems in nursery and early childhood, Meltzer develops Bion’s concept of a nonthinking ‘basic assumption’ mentality, setting it against the individual mind, which grows through the digestion of emotional and passionate experiences. This distinction is crucial for the comprehension of some of the darkest areas of psychoanalytic practice: infantile disturbances, the functioning of adolescent groups, and somatizations.