Though the _quidam_ alluded to by Cicero looked upon the obscure sentence in Plato's Timaeus as a dim indication of the theory of Hicetas, yet the two agree only in the supposition of a rotation of the earth, and differ essentially in the pervading cosmical conceptions. Hicetas states distinctly that which his theory denies, as well as that which it affirms. The negation of the celestial rotations, is in his theory a point of capital and coordinate importance, on which he contradicts both Plato and Aristotle as well as the apparent evidence of sense. I cannot suppose that this theory can have been proclaimed or known to Aristotle when his works were composed: for the celestial revolutions are the keystone of his system, and he could hardly have abstained from combating a doctrine which denied them altogether. In the hands of Hicetas (perhaps in those of Herakleides, if we may believe what is said about him) astronomy appears treated as a science by itself, with a view "to provide such hypotheses as may save the phenomena" ([Greek: sô/zein ta\ phaino/mena], Simpl. ad Aristot. De Coelo, p. 498, Schol. Brandis). It becomes detached from those religious, ethical, poetical, teleological, arithmetical decrees or fancies, in which we see it immersed in the Platonic Timaeus, and even (though somewhat less) in the Aristotelian Treatise De Coelo. Hence the meaning of Plato, obscurely announced from the beginning, ceased to be understood: the solid revolving axis of the Kosmos, assumed without being expressly affirmed in his Timaeus, dropped out of sight: the doctrine of the rotation of the earth was presented in a new point of view, as a substitute for the celestial revolutions. But no proper note was taken of this transition. The doctrine of Plato was assumed to be the same as that of Hicetas. When we read Plutarch's criticism (Quæst. Plat. p. 1006 C) upon the word [Greek: i)llome/nên], we see that he puts to himself the question thus--"Does Plato in the Timæus conceive the earth as kept together and stationary--or as turning round and revolving, agreeably to the subsequent theory of Aristarchus and Seleukus?" Here we find that Plutarch conceives the alternative thus--Either the earth does not revolve at all, or it revolves as Aristarchus understood it. One or other of these two positions must have been laid down by Plato in the Timæus.--So we read in Plutarch. But the fact is, that Plato meant neither the one nor the other. The rotation of the earth round the solid cosmical axis, which he affirms in the Timæus--is a phenomenon utterly different from the rotation of the earth as a free body round the imaginary line called its own axis, which was the doctrine of Aristarchus.