heaven and sun in twenty-four hours, there is no way of accounting for the
alternation of day and night; since the equal motion of the earth and sun
would have the effect of absolute immobility. To which it may be replied
that Plato never says that the earth goes round with the outer heaven and
sun; although the whole question depends on the relation of earth and sun,
their movements are nowhere precisely described. But if we suppose, with
Mr. Grote, that the diurnal rotation of the earth on its axis and the
revolution of the sun and outer heaven precisely coincide, it would be
difficult to imagine that Plato was unaware of the consequence. For though
he was ignorant of many things which are familiar to us, and often confused
in his ideas where we have become clear, we have no right to attribute to
him a childish want of reasoning about very simple facts, or an inability
to understand the necessary and obvious deductions from geometrical figures
or movements. Of the causes of day and night the pre-Socratic
philosophers, and especially the Pythagoreans, gave various accounts, and
therefore the question can hardly be imagined to have escaped him. On the
other hand it may be urged that the further step, however simple and
obvious, is just what Plato often seems to be ignorant of, and that as
there is no limit to his insight, there is also no limit to the blindness
which sometimes obscures his intelligence (compare the construction of
solids out of surfaces in his account of the creation of the world, or the
attraction of similars to similars). Further, Mr. Grote supposes, not that
(Greek) means 'revolving,' or that this is the sense in which Aristotle
understood the word, but that the rotation of the earth is necessarily
implied in its adherence to the cosmical axis. But (a) if, as Mr Grote
assumes, Plato did not see that the rotation of the earth on its axis and
of the sun and outer heavens around the earth in equal times was
inconsistent with the alternation of day and night, neither need we suppose
that he would have seen the immobility of the earth to be inconsistent with
the rotation of the axis. And (b) what proof is there that the axis of the