ABSTRACT
THERE are two central ideas which emerge from the preceding chapters. The first is that the origin of classification is to be sought in graphic collections, where the role of spatial configuration is less overriding than it is in perceptual structures, but is nonetheless far from insignificant, as is the case with operational structures governed by relations of inclusion. The second is that the development from graphic structures to operational structures depends on a complex interplay of retroactive and anticipatory activities. These may be grouped together under the heading of “representative regulations”. We now know that they prepare the way for operational reversibility.
