The author attempts to correlate biological and psychological drive strengths with cognitive development. He concludes that an optimum level of pubertal instinctual danger promotes long-term intellectual and social growth. To support his thesis he cites two studies: one, a thirty-year longitudinal research pertaining to the length of prepuberty and puberty as determined by the age of onset of puberty; the other, a correlation of the prepubertal and pubertal outcomes of two kinds of early childhood environments in which there was exposure to greater or lesser amounts of psychosexual stimulation. Peskin reproaches psychoanalysis for neglecting the soma in the understanding of developmental schedules and maintains that keeping the somatic and psychodynamic levels in simultaneous focus would be enlightening.