=195.= Thus early in their theory the Stoics were led to make two assertions on questions of scientific fact, in which they opposed the best scientific opinion of their own time. For many authorities held that the earth revolved on its axis, and that the revolution of the sky was only apparent. Such were HICETAS of Syracuse[26], a Pythagorean philosopher, whose views were quoted with approval by Theophrastus, and later ECPHANTUS the Pythagorean, and HERACLIDES of Pontus[27]. From the point of view of astronomical science this view seemed well worthy of consideration, as Seneca in particular emphasizes[28]. Other astronomers had gone further, declaring that the sun lay in the centre, and that the earth and other planets revolved round it. Theophrastus stated that Plato himself in his old age had felt regret that he had wrongly placed the earth in the centre of the universe; and the heliocentric view was put forward tentatively by ARISTARCHUS of Samos, and positively by the astronomer SELEUCUS, in connexion with the theory of the earth’s rotation[29]. For this Cleanthes had said that the Greeks should have put Aristarchus on trial for impiety, as one who proposed to disturb ‘the hearth of the universe[30].’ This outburst of persecuting zeal, anticipating so remarkably the persecution of Galileo, was effective in preventing the spread of the novel doctrine. Posidonius was a great astronomer, and recognised the heliocentric doctrine as theoretically possible[31]; indeed, as one who had himself constructed an orrery, shewing the motion of all the planets[32], he must have been aware of its superior simplicity. Nevertheless he opposed it vigorously on theological grounds, and perhaps more than any other man was responsible for its being pushed aside for some 1500 years[33]. The precise ground of the objection is not made very clear to us, and probably it was instinctive rather than reasoned. It could hardly be deemed impious to place the sun, whom the Stoics acknowledged as a deity, in the centre of the universe; but that the earth should be reckoned merely as one of his attendant planets was humiliating to human self-esteem, and jeopardised the doctrine of Providence, in accordance with which the universe was created for the happiness of gods and men only. [Sidenote: The elements.]