perficial play of sense and opinion
is what all practical reason must assume and what all comprehended
experience bears witness to. A cosmos does not mean a disorder with
which somebody happens to be well pleased; it means a necessity from
which every one must draw his happiness. If a principle is efficacious
it is to that extent mechanical. For to be efficacious a principle must
apply necessarily and proportionately; it must assure us that where the
factors are the same as on a previous occasion the quotient will be the
same also.

Now, in order that the flux of things should contain a repetition,
elements must be identified within it; these identical elements may then
find themselves in an identical situation, on which the same result may
ensue which ensued before. If the elements were not constant and
recognisable, or if their relations did not suffice to determine the
succeeding event, no observation could be transferred with safety from
the past to the future. Thus art and comprehension would be defeated
together. Novelties in the world are not lacking, because the elements
entering at any moment into a given combination have never before
entered into a combination exactly similar. Mechanism applies to the
matter and minute texture of things; but its applying there will create,
at each moment, fresh ideal wholes, formal unities which mind emanates
from and represents. The result will accordingly always be unprecedented
in the total impression it produces, in exact proportion to the
singularity of the situation in hand. Mechanical processes are not like
mathematical relations, because they _happen_. What they express the
form of is a flux, not a truth or an ideal necessity. The situation may
therefore always be new, though produced from the preceding situation by
rules which are invariable, since the preceding situation was itself
novel.

Mechanism might be called the dialectic of the irrational. It is such a
measure of intelligibility as is compatible with flux and with
existence. Existence itself being irrational and change unintelligible,
the only necessity they are susceptible of is a natural or empirical
necessity, impinging at both ends upon brute matters of fact. The
existential elements, their situation, number, affinities, and mutual
influence all have to be begged before calculation can begin. When these
surds have been accepted at their face value, inference may set to work
among them; yet the inference