The marriage of the King and Queen of May intended to promote the growth
of vegetation by homoeopathic magic; intercourse of the sexes practised
to make the crops grow and fruit-trees to bear fruit; parents of twins
supposed to fertilise the bananas in Uganda; relics of similar customs
in Europe; continence practised in order to make the crops grow; incest
and illicit love supposed to blight the fruits of the earth by causing
drought or excessive rain; traces of similar beliefs as to the blighting
effect of adultery and incest among the ancient Jews, Greeks, Romans,
and Irish; possible influence of such beliefs on the institution of the
forbidden degrees of kinship; explanation of the seeming contradiction
of the foregoing customs; indirect benefit to humanity of some of these
superstitions.