computed and
predicted, there was nothing further to be done; explanation was
exhausted. Unless we can find some other force to fraternise with
gravity, so that the two might become a still more comprehensive unity,
we must rest in gravity as the ultimatum of our faculties. There is no
conceivable modification, or substitute, that would better our position.
Before Newton, it was a mystery what kept the moon and the planets in
their places; the assimilation with falling bodies was the solution.
But, say many persons, is not gravity itself a mystery? We say No;
gravity has passed through all the stages of legitimate and possible
explanation; it is the most highly generalised of all physical facts,
and by no assignable transformation could it be made more intelligible
than it is. It is singularly easy of comprehension; its law is exactly
known; and, excepting the details of calculation, in its more complex
workings, there is nothing to complain of, nothing to rectify, nothing
to pretend ignorance about; it is the very pattern, the model, the
consummation of knowledge. The path of science, as exhibited in modern
times, is towards generality, wider and wider, until we reach the
highest, the widest laws of every department of things; there
explanation is finished, mystery ends, perfect vision is gained.

* * * * *

What is always reckoned the mystery by pre-eminence is the union of BODY
and MIND. How, then, should we treat this Mystery according to the
spirit of modern thought, according to the modern laws of explanation?
The course is to _conceive_ the elements according to the only possible
plan, our own sensibility or consciousness; which gives us matter as one
class of facts--extension, inertness, weight, and so on; and mind as
another class of facts--pleasures, pains, volitions, ideas. The
difference between these two is total, diametrical, complete; there is
really nothing common to the experience of pleasure and the experience
of a tree; difference has here reached its _acme_; agreement is
eliminated; there is no higher genus to include these two in one; as the
ultimate, the highest elements of knowledge, they admit of 110 fusion,
no resolution, no unity. Our utmost flight of generality leaves us in
possession of a double, a _couple_ of absolutely heterogeneous elements.
Matter cannot be resolved into mind; mind cannot be resolved into
matter; each has its own definition; each negatives