Oneiromancy has thus slowly degenerated to folk-lore and superstition. But at the outset it possessed something of the combined dignities of religion and of science. Not only were the old dream interpreters careful of the significance and results of individual dreams, in order to build up a body of doctrine, but they held that not every dream contained in it a divine message; thus they would not condescend to interpret dreams following on the drinking of wine, for only to the temperate, they declared, do the gods reveal their secrets.[141] The serious and elaborate way in which the interpretation of dreams was dealt with is well seen in the treatise on this subject by Artemidorus of Daldi, a native of Ephesus, and contemporary of Marcus Aurelius.[142] He divided dreams into two classes: _theorematic_ dreams, which come literally true, and _allegorical_ dreams. The first group may be said to correspond to the modern groups of prophetic and proleptic or prodromic dreams, while the second group includes the symbolical dreams which have of recent years again attracted attention. Synesius, who lived in the fourth century, and eventually became a Christian bishop without altogether ceasing to be a Greek pagan, wrote a very notable treatise on dreaming, in which, with a genuinely Greek alertness of mind, he contrived to rationalise and almost to modernise the ancient doctrine of dream symbolism. He admits that it is in their obscurity that the truth of dreams resides, and that we must not expect to find any general rules in regard to dreams; no two people are alike, so that the same dream cannot have the same significance for every one, and we have to find out the rules of our own dreams. He had himself (like Galen) often been aided in his writings by his dreams, in this way getting his ideas into order, improving his style, and receiving criticisms of extravagant phrases. Once, too, in the days when he hunted, he invented a trap as a result of a dream. Synesius declares that attention to divination by dreams is good on moral grounds alone. For he who makes his bed a Delphian tripod will be careful to live a pure and noble life. In that way he will reach an end higher than that he aimed at.[143] It seems to-day by no means improbable that, amid the absurdities of this popular oneiromancy, there are some items of real significance. Until recent years, however, the absurdities have frightened away the scientific investigator. Almost the only investigator of the psychology of dreaming who ventured to admit a real symbolism in the dream world was Scherner,[144] and his arguments were not usually accepted nor even easy to accept. When we are faced by the question of definite and constant symbols it still remains true that scepticism is often called for. But there can be no manner of doubt that our dreams are full of symbolism.[145]