LET. II.

OF THE EARTH.

27

return nearly to the same places in the heavensagain in twenty-four hours, it follows that theymust really move, as they appear to do, or elsethat we ourselves must be moved, and attributeour motion to them: it being a self-evident'principle, that, if two things change their situ-ation with respect to each other, one of them, atleast, must be moved.

But if this change be owing to the revolutionof the stars, we must suppose them to be en-dowed with a motion so amazingly swift as toexceed all conception. Since it is now known,by calculations founded on the surest observa-tions, that their distances from us are so im-»mense, and the orbits they have to run round soprodigioufly great, that the nearest of themwould move at least 100,000 miles in a minute.Now as nature never does that in a complicatedand laborious manner which may be done in amore simple and easy one; it is certainly moreagreeable to reason, as well as to the power andwisdom of the Creator, that these effects shouldbe produced by the motion of the earth ; especi-ally as such a motion will best account for allthe celestial appearances, and, at the same time,preserve that beautiful simplicity and harmony,which is found to prevail in every other part ofthe creation.

And this argument will appear still more forci-ble, if we compare the vast bulk of the celestial

bodies