  Two modifications of this Aristotelian conception have been particularly influential in the last century and a half. One is the 19th century idea that ontogeny recapitulates phylogeny (Gould, 1977), that is, that the development of an individual recapitulates the history and evolutionary development of the race, or species (Spock, 1968, 229). This idea is prominent in Freud (1950) and in the early writings of Jean Piaget (see, e.g. Piaget, 1933). Piaget, however, sought in his later writings to explain the phenomenon of recapitulation by appeal to general principles of structural change in cognitive development (see, e.g., Piaget, 1968, 27).