Barlaam also took exception to the doctrine held by the Hesychasts as to the uncreated nature of the light, the experience of which was said to be the goal of Hesychast practice, regarding it as heretical and blasphemous. It was maintained by the Hesychasts to be of divine origin and to be identical to the light which had been manifested to Jesus' disciples on Mount Tabor at the Transfiguration. Barlaam viewed this doctrine of uncreated light to be polytheistic because as it postulated two eternal substances, a visible and an invisible God. Barlaam accuses the use of the Jesus Prayer as being a practice of Bogomilism.