The classical instance of the development of this idea is found in the cult of the Greek Hestia, the Latin Vesta, a goddess who was the personification of fire, the guardian of the household altar and of the welfare of cities and nations. She was worshipped fairly widely in Greece and Asia Minor, but principally in Rome, where a beautiful circular temple was dedicated to her service; her ministers, the Vestal virgins, were held in the greatest honour and were chosen from among the loveliest and noblest of Roman maidens. In this temple was kept ever brightly burning the sacred fire supposed to have been kindled by the rays of the sun, and to have been brought by AEneas when he founded his kingdom in the new land of Italy. The extinction of this fire would have been regarded as the gravest public calamity, foreboding disaster. Its flames were intended to represent the _purity_ of the goddess, thus emphasising the mystic aspect of another physical property of fire--its purifying power. "Our God" (said the writer of the Epistle to the Hebrews) "is a consuming fire." Greece had its common hearth at Delphi. It was also supposed that at the centre of the earth there was a hearth which answered to that. In the Apocalypse we read of the altar with its sacred fire as central in heaven. Truly these concepts are persistent! And why? Because there is more than imagination in them; they are the products of ideas immanent in the material phenomena in which they are embodied, and through which they manifest themselves to the human soul. There could not fail to be fire-gods many, and a study of their respective characters, especially in the earlier stages of their development, often furnishes a key to the intuitional workings of the primitive mind as prompted by the always arresting, and often terrorising phenomena of fire and flame. Max Müller's detailed study of the development of the Hindu god, Agni, was mentioned in an earlier chapter. The name originally means the Mover, and arose, doubtless, from the running, darting, leaping movement of flame. Beginning his career as a purely physical god, he advanced through various stages of spiritualisation until he became the supreme deity. Is not the problem of motion still one of the most fascinating and profound? Bergson's "L'Evolution créatrice" is one of the latest attempts to grapple with it, and those who in early India personified fire as the Mover were his legitimate predecessors.