vided into _celestial
physics_ and _terrestrial physics_--the phenomena presented by the
universe, and the phenomena presented by earthly bodies. If now
celestial bodies and terrestrial bodies exhibit sundry leading phenomena
in common, as they do, how can the generalisation of these common
phenomena be considered as pertaining to the one class rather than to
the other? If inorganic physics includes geometry (which M. Comte has
made it do by comprehending _geometrical_ astronomy in its
sub-section--celestial physics); and if its sub-section--terrestrial
physics, treats of things having geometrical properties; how can the
laws of geometrical relations be excluded from terrestrial physics?
Clearly if celestial physics includes the geometry of objects in the
heavens, terrestrial physics includes the geometry of objects on the
earth. And if terrestrial physics includes terrestrial geometry, while
celestial physics includes celestial geometry, then the geometrical part
of terrestrial physics precedes the geometrical part of celestial
physics; seeing that geometry gained its first ideas from surrounding
objects. Until men had learnt geometrical relations from bodies on the
earth, it was impossible for them to understand the geometrical
relations of bodies in the heavens.

So, too, with celestial mechanics, which had terrestrial mechanics for
its parent. The very conception of _force_, which underlies the whole of
mechanical astronomy, is borrowed from our earthly experiences; and the
leading laws of mechanical action as exhibited in scales, levers,
projectiles, etc., had to be ascertained before the dynamics of the
solar system could be entered upon. What were the laws made use of by
Newton in working out his grand discovery? The law of falling bodies
disclosed by Galileo; that of the composition of forces also disclosed
by Galileo; and that of centrifugal force found out by Huyghens--all of
them generalisations of terrestrial physics. Yet, with facts like these
before him, M. Comte places astronomy before physics in order of
evolution! He does not compare the geometrical parts of the two
together, and the mechanical parts of the two together; for this would
by no means suit his hypothesis. But he compares the geometrical part of
the one with the mechanical part of the other, and so gives a semblance
of truth to his position. He is led away by a verbal delusion. Had he
confined his attention to the things and disregarded the