The Golden Bough: A Study in Magic and Religion (Third Edition, Vol. 02 of 12)
Chapter XXI.—Dianus and Diana Pp. 376-387
Recapitulation: rise of sacred kings endowed with magical or divine powers; the King of the Wood at Nemi seems to have personified Jupiter the god of the oak and to have mated with Diana the goddess of the oak; Dianus (Janus) and Diana originally dialectically different forms of Jupiter and Juno; Janus (Dianus) not originally a god of doors; double-headed figure of Janus (Dianus) derived from a custom of placing him as sentinel at doorways; parallel custom among the negroes of Surinam; originally the King of the Wood at Nemi represented Dianus (Janus), a duplicate form of Jupiter, the god of the oak, the thunder, and the sky.
INDEX Pp. 389-417