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it by language, its family, and its school, or does the child itself provide spontaneous productions which may have had some influence, if generalized, on more primitive societies than our own" (1971, p. 83). The sequences run in parallel, but neither causes the other. They both follow similar paths because a common object (the preconscious mind) is pursuing a common history of development (successive assimilations of external reality to produce a sequence in modes of reasoning).
Ironically, Piaget's contemporary explanation of parallels between ontogeny and phylogeny harks back to the earliest theory of all—the Meckel-Serres law of early nineteenth-century Naturphilosophie and transcendental morphology. The Naturphilosophen attributed parallels not to any interaction of one sequence with another (as Haeckel was later to require), but to a common constraint—the single direction of all development—acting separately on two independent sequences. One hundred years later, Hertwig (see Chapter 6, note 30) proposed a different correspondence theory, refuting Haeckel's biogenetic law while affirming the parallels between ontogeny and phylogeny. Hertwig saw the laws of physics and chemistry as a common external constraint. Given a small and simple starting point (the phyletic amoeba or the ontogenetic zygote), nature can only build complexity in a limited number of ways. Piaget uses the same style of argument, however different the content. The parallels are real, but phylogeny does not cause ontogeny. Again, two independent sequences follow similar paths under the influence of a common constraint—the structure of the human mind itself.
In an outrageously mixed metaphor with agricultural and geological components, G. Stanley Hall proclaimed the educational potential of recapitulation:
Children thus in their incomplete stage of development are nearer the an- imals in some respects than they are to adults, and there is in this direction a rich but undiscovered silo of educational possibilities which heredity has stored up like the coal-measures, which when explored and utilized to its full extent will reveal pedagogic possibilities now undreamed of. (1904, 2: 221–222)
Hall would have preferred a "school" of nature for young children—a real opportunity to relive the phyletic past as our ancestors did. But he accepted the practical necessity of professional teachers and school buildings. Still, if repetition of phylogeny were repressed