titative prevision is reached
deductively; induction can achieve only qualitative prevision." Now, if
we remember that the very first accurate quantitative law of physical
phaenomena ever established, the law of the accelerating force of
gravity, was discovered and proved by Galileo partly at least by
experiment; that the quantitative laws on which the whole theory of the
celestial motions is grounded, were generalized by Kepler from direct
comparison of observations; that the quantitative law of the
condensation of gases by pressure, the law of Boyle and Mariotte, was
arrived at by direct experiment; that the proportional quantities in
which every known substance combines chemically with every other, were
ascertained by innumerable experiments, from which the general law of
chemical equivalents, now the ground of the most exact quantitative
previsions, was an inductive generalization; we must conclude that Mr
Spencer has committed himself to a general proposition, which a very
slight consideration of truths perfectly known to him would have shown
to be unsustainable.

Again, in the very pamphlet in which Mr Spencer defends himself against
the supposition of being a disciple of M. Comte ("The Classification of
the Sciences," p. 37), he speaks of "M. Comte's adherent, Mr Buckle."
Now, except in the opinion common to both, that history may be made a
subject of science, the speculations of these two thinkers are not only
different, but run in different channels, M. Comte applying himself
principally to the laws of evolution common to all mankind, Mr Buckle
almost exclusively to the diversities: and it may be affirmed without
presumption, that they neither saw the same truths, nor fell into the
same errors, nor defended their opinions, either true or erroneous, by
the same arguments. Indeed, it is one of the surprising things in the
case of Mr Buckle as of Mr Spencer, that being a man of kindred genius,
of the same wide range of knowledge, and devoting himself to
speculations of the same kind, he profited so little by M. Comte.

These oversights prove nothing against the general accuracy of Mr
Spencer's acquirements. They are mere lapses of inattention, such as
thinkers who attempt speculations requiring that vast multitudes of
facts should be kept in recollection at once, can scarcely hope always
to avoid.

[8] We refer particularly to the mystical metaphysics connected with the
negative sign, imaginary quantities, infi