The term ‘Manichaean’ has come to be regarded as synonymous with a radical dualistic perspective, and is now utilised in all sorts of contexts such as literature and politics. Gardner examines what can be known of the actual teachings of the third‑century sage and self‑declared ‘Apostle of Jesus Christ’ known as Mani or Manichaios. His extant writings are surveyed in order to determine what he says about the nature of God and the origin of matter and evil. Particular attention is given to the terminology and symbolism applied to the idea of two eternal and opposite principles, the kingdoms of light and darkness. Gardner considers possible origins for Mani’s teachings in the Judaeo‑Christian, Gnostic and Iranian traditions ; together with the question of further developments within the community after its founder’s death.