The earliest 'defensive measures' arise ontogenetically in direct or reflex physical fashion. The body's use of water, for example, was originally a simple physical act. Later, the 'use of water' takes on a variety of psychophysical aspects and functions: as a 'mechanical pad protection', as a solvent of irritants, as a cooling agent, as a major element in chemical balance, and others. In other psychophysical responses, intrapsychic checks have become part of what would otherwise remain more or less simple physical reactions: internal ego differences now modify basic aggressive-defensive physical behavior. Greenacre poses certain questions about these speculations: What are the connections between the earliest physical reactions and later complex defensive processes? What are the problems of transition from stage to stage in development? What early conditions shape the later choice of special defense mechanisms? This paper deals with the influence of events while the primary process predominates.