A conspicuous disharmony appears in the ground-plan of human development. Whereas man's growth is subject to a remarkable deceleration, the processes of maturation in the id run their course according to a primordial, unretarded schedule. There is an intimate connexion between the evolution of this developmental disharmony and the peculiar capacity of the psychic apparatus for introjection and identification. These mechanisms, making their first appearance at the human level, made possible psychic provision for the inhibition and binding of prematurely erupting drive tensions. They are the basis for a primary, biologically grounded defence structure. Lincke presents the genesis and stepwise construction of this nucleus of the ego. He relates personality development to the successive maturation of inherited id structures which used to regulate communal life at the animal level and then underwent a 'reformulation' in the case of man.