The dreams which appear to the soul through God’s love are unerring criteria of its health. Such dreams do not change from one shape to another… they approach the soul and fill it with spiritual gladness… Demonic fantasies, however, … do not keep the same shape or maintain a constant form for long… The safest rule is never to trust to anything that appears to us in our dreams. For dreams are generally nothing more than images reflecting our wandering thoughts, or else they are the mockery of demons.
— St Diadochos of Photiki "On Spiritual Knowledge and Discrimination" VI 264 - 37