The monkish encyclopedists Theories regarding the rainbow and the causes of storms Meteorological phenomena attributed to the Almighty II. Diabolical Agency in Storms. Meteorological phenomena attributed to the devil--"the prince of the power of the air" Propagation of this belief by the medieval theologians Its transmission to both Catholics and Protestants--Eck, Luther The great work of Delrio Guacci's Compendium The employment of prayer against "the powers of the air" Of exorcisms Of fetiches and processions Of consecrated church bells III. The Agency of Witches. The fearful results of the witch superstition Its growth out of the doctrine of evil agency in atmospheric phenomena Archbishop Agobard's futile attempt to dispel it Its sanction by the popes Its support by confessions extracted by torture Part taken in the persecution by Dominicans and Jesuits Opponents of the witch theory--Pomponatius, Paracelsus, Agrippa of Nettesheim Jean Bodin's defence of the superstition Fate of Cornelius Loos Of Dietrich Flade