In the first place, granting Plato to have believed in the motion of the earth, can we also assume that he would necessarily have asserted it with distinctness and emphasis, as M. Cousin contends? I think not. Gruppe maintains exactly the contrary; telling us that Plato's language was intentionally obscure and equivocal--from fear of putting himself in open conflict with the pious and orthodox sentiment prevalent around him. I do not carry this part of the case so far as Gruppe, but I admit that it rests upon a foundation of reality. When we read (Plutarch, De Facie in Orbe Lunæ, p. 923) how the motion of the earth, as affirmed by Aristarchus of Samos (doubtless in a far larger sense than Plato ever imagined, including both rotation and translation), was afterwards denounced as glaring impiety, we understand the atmosphere of religious opinion with which Plato was surrounded. And we also perceive that he might have reasons for preferring to indicate an astronomical heresy in terms suitable for philosophical hearers, rather than to proclaim it in such emphatic unequivocal words, as might be quoted by some future Melêtus in case of an indictment before the Dikasts. We must remember that Plato had been actually present at the trial of Sokrates. He had heard the stress laid by the accusers on astronomical heresies, analogous to those of Anaxagoras, which they imputed to Sokrates--and the pains taken by the latter to deny that he held such opinions (see the Platonic Apology). The impression left by such a scene on Plato's mind was not likely to pass away: nor can we be surprised that he preferred to use propositions which involved and implied, rather than those which directly and undisguisedly asserted, the heretical doctrine of the earth's rotation. That his phraseology, however indirect, was perfectly understood by contemporary philosophers, both assentient and dissentient, as embodying his belief in the doctrine--is attested by the two passages of Aristotle.