“…Using evidence mainly from California, Amazonia and northern and north-western Australia, I will argue that the cultural assumptions underlying shamanism or 'medicine' in these areas run roughly as follows: (1) health is dependent upon the maintenance of a correct 'balance' between states or forces such as heat and cold, wetness and dryness, blood and fire, kinship unity and sex, or 'rawness' and the state of being 'cooked' -forces, that is, which are conceptualised as polar opposites of the kind which make up the structure of the world; (2) nature achieves her own health by alternating in a balanced way between these opposites -as between dry season and wet, full moon and dark, day and night, life and temporary or periodic 'death'; (3) the health of the human individual presupposes the ability correctly to reduplicate, within the body itself, these rhythms of periodic renewal; (4) ideally, women should do this by menstruating in synchrony with one another and with the moon, thus providing a collective social rhythm through which human society can keep 'in phase' with the self-renewing processes of the wider cosmos; (5) failing this, men themselves must learn to 'menstruate' in some symbolic sense in order to safeguard the rhythms on which human health depends.…”