Crying is described as the combination of four separate, yet overlapping, emotional states which the author feels originate in intrauterine life. Screaming represents the protest at being born and being alive; sobbing is based on the mother's labor; weeping reflects the foetus's existence in the amniotic fluid; depression is anchored in the archaic period of embryonic development (from conception to about eight weeks). The author feels that crying in its various manifestations occurs when the infant meets with frustration and at such times the crying represents an attempt 'to return to those intrauterine modes of existence previously experienced'.