This chapter examines the neuromolecular and plastic brain. Ideas about plasticity and the openness of brains to environment influences, from initial evidence about nerve development, through the recognition that synaptic plasticity was the very basis of learning and memory, to evidence about the influence of environment on gene expression and the persistence throughout life of the capacity to make new neurons—all this made the neuromolecular brain seem exquisitely open to its milieu, with changes at the molecular level occurring throughout the course of a human life and thus shaping the growth, organization, and regeneration of neurons and neuronal circuits at time scales from the millisecond to the decade. This was an opportunity to explore the myriad ways in which the milieu got “under the skin,” implying an openness of these molecular processes of the brain to biography, sociality, and culture, and hence perhaps even to history and politics.