nalyse.

Since then the process of mathematical synthesis in science has been
carried many stages further. The exponents of this aspect of scientific
progress, of whom we may take the late M. Henri Poincare as the leading
representative in our generation, are perfectly justified in treating
this gradual mathematical unification of knowledge with pride and
confidence. They have solid achievement on their side. It is through
science of this kind that the idea of universal order has gained its
sway in man's mind. The occasional attacks on scientific method, the
talk one sometimes hears of 'breaking the fetters of Cartesian
mechanics', seem to suggest that the great structure which Galileo,
Newton, and Descartes founded is comparable to the false Aristotelianism
which they destroyed. The suggestion is absurd: its chief excuse is the
desire to defend the autonomy of the sciences of life, about which we
have a word to say later on. But we must first complete our brief
mention of the greatest stages on the mechanical side, of which a full
and vivid account may be found in such a book as M. Poincare's _Science
et Hypothese_.

Early in the nineteenth century a trio of discoverers, a Frenchman, a
German, and an Englishman, established the theory of the conservation of
energy. To the labours of Sadi Carnot, Mayer, and Joule is due our
knowledge of the fact that heat which, as a supposed entity, had
disturbed the physics and chemistry of the earlier centuries, was itself
another form of mechanical energy and could be measured like the rest.
Later in the century another capital step in synthesis was taken by the
foundation of astrophysics, which rests on the identity of the physics
and chemistry of the heavenly bodies with those of the earth.

The known universe thus becomes still more one. Later researches again,
especially those of Maxwell, tend to the identification of light and
heat with electricity, and in the last stage matter as a whole seems to
be swallowed up in motion. It is found that similar equations will
express all kinds of motion; that all are really various forms of the
motion of something which the mind postulates as the thing in motion; we
have in each case to deal with wave-movements of different length. The
broad change, therefore, which has taken place since the mechanics of
Newton is the advance from the consideration of masses to that of
molecules of smaller and smaller size, and the truth of the former is