" Development is a central notion in psychology, because it is not simply 'development.' It is a paradoxical notion because it supposes neither absolute continuity nor absolute discontinuity...Development is characterized by the emergence of new forms which are motivated by previous phases...auto-transformation, bonds prepared by previous acquisitions, and movement modifying its own movement. Reciprocal action between inside and outside exists,,,Quantitative accumulation phenomena produce qualitative changes...quick acquisitions followed by plateaus...(level phenomena). "

― Maurice Merleau-Ponty , Child Psychology and Pedagogy: The Sorbonne Lectures 1949-1952