rs and
the firmament; what in the world they would have to wonder at in the case
of their ninth sphere, let them imagine as they like. But to feign a
_Primum Mobile_ and to attribute to the thing thus feigned a motion to be
completed in the space of 24 hours, and not to allow this motion to the
Earth in the same interval of time, is absurd. For a great circle of the
Earth is to the ambit of the _Primum Mobile_ less than a furlong to the
whole Earth. If the diurnal rotation of the Earth seem headlong, and not
admissible in nature by reason of its rapidity, worse than insane will be
the movement of the _Primum Mobile_ both for itself and the whole universe,
agreeing as it does with no other motion in any proportion or likeness. It
seems to Ptolemy and the Peripateticks that nature must be disordered, and
the framework and structure of this globe of ours be dissolved, by reason
of so swift a terrestrial revolution. The Earth's diameter is 1718 German
miles; the greatest elongation of the new Moon is 65, the least is 55
semi-diameters of the Earth: the greatest altitude of the half moon is 68,
the least 52: yet it is probable that its sphaere is still larger and
deeper. The sun in its greatest eccentricity has a distance of 1142
semi-diameters of the Earth; Mars, Jupiter, Saturn, being slower in motion,
are so proportionately further remote from the Earth. The distances of the
firmament and of the fixed stars seem to the best mathematicians
inconceivable. Leaving out the ninth sphaere, if the convexity of the
_Primum Mobile_ be duly estimated in proportion to the rest of the
sphaeres, the vault of the _Primum Mobile_ must in one hour run through as
much space as is comprised in 3000 great circles of the Earth, for in the
vault of the firmament it would complete more than 1800; but what iron
solidity can be imagined so firm and tough as not to be disrupted and
shattered to fragments by a fury so great and a velocity so ineffable. The
Chaldaeans indeed would have it that the heaven consists of light. In
light, however, there is no so-great firmness, neither is there in
Plotinus' fiery firmament, nor in the fluid or aqueous or supremely rare
and transparent heaven of the divine Moses, which does not cut off from our
sight the lights of the stars. We must accordingly reject the so deep-set
error about this so mad and furious a celestial velocity, and the forced
retardation of the rest of the heavens. Let theologians discard and wi