Abstract
Piaget’s notion of the permanent object is elaborated as the logical competence to construct mental objects, ushering in a new developmental stage of mind beyond sensorimotor action. The claim is made that mind and mental objects form a societal mental structure that enables children to assimilate their society and become its active co-constructing members. Specific developmental achievements, beginning at approximately age 2 years, are noted as evidence for the claim that the competence to create mental objects as well as symbols and meanings separated from action is in fact the evolutionarily evolved human capacity for society and culture. Vygotsky’s idea of a natural line of development refers to the general human competence that is always presupposed in any study of the specific cultural line of development.