The Druids proper (_Eubages_, they were called in Gaul) were philosophers as well as scholars, perhaps even magicians, for magic was at that time nothing more than the outward form of science. They were charged with the maintenance of the principles of morality, and had to study the secrets of nature. The Prophets, on the other hand, knew how to interpret in the slightest breath of wind, the language of the holy oak, which spoke to them in the rustling of its leaves, in the soughing of the branches, in the low cracking heard within the trunk, and even in the earlier or later appearance of the foliage. There were, finally, the Bards, poets bound to the altar. While the bards were singing around the oak, the prophets caused it to render its oracles. These oracles soon increased largely not only in Europe, but also in Asia Minor, where a Celtic colony, according to Herodotus, established in the land they had conquered the oracle of Dodona. Early Greece worshipped an oak tree, which Strabo, however, assures {041}us was a beech. There is no disputing about trees any more than about colors; but Homer calls it an oak, and an oak it must remain for us. [Illustration: 061] This new movement, grafted upon the simple worship of the Druids, did not stop here. After having for some time been accustomed to converse with Teut by means of a tree, the Celts were naturally surprised at seeing that, while trees could speak, living creatures remained silent, and were apparently deprived of the power of foretelling the future. Certain chieftains, especially, felt aggrieved, {042}upon setting out on a great campaign, that they were not allowed to carry the holy oak along with them, and in their intense devotion, fell upon the idea of consulting the nervous trembling of their horses and their sudden neighing in moments of surprise or terror,--for in order to be of prophetic nature the movements of the animals had to be involuntary and spontaneous. As this creed began to spread gradually, every man who was setting out on a journey or a warlike expedition mounted his horse in the firm conviction that he would be able to consult his four-footed prophet at any time during his absence from home, provided he was able to submit the omens to the learned interpretations of a soothsayer. The Druid priests were not long in becoming seriously alarmed at these travelling oracles, liable as they naturally were to contradict each other. As they had before chosen a single tree to be the sacred tree, so they now accepted as genuine omens only the symptoms noticed in certain horses which were bred within the sacred precincts and under their own eyes.