ABSTRACT
The problem of stages* in the mental development of the child is the fundamental problem of child psychology. The elaboration of this problem has important theoretical significance since it is by determining the stages of mental development and by discovering the patterns of transition from one stage to the next that psychology eventually will solve the problem of the motive forces of mental development. We contend that every conception of the motive forces of mental development must first of all be tested on the "proving grounds" of a theory of developmental stages.
