t the
former is enriched with content and the latter are made intelligible--a
veritable conquest and valid possession for mankind. And in this labour
of proof, science and philosophy alike take their share.

Philosophy may be said to come midway between poetry and science, and to
partake of the nature of both. On the one side it deals, like poetry,
with ideals of knowledge, and announces truths which it does not
completely verify; on the other, it leaves to science the task of
articulating its principles in facts, though it begins the articulation
itself. It reveals subsidiary principles, and is, at the same time, a
witness for the unity of the categories of science. We may say, if we
wish, that its principles are mere hypotheses. But so are the ideas
which underlie the most practical of the sciences; so is every forecast
of genius by virtue of which knowledge is extended; so is every
principle of knowledge not completely worked out. To say that philosophy
is hypothetical implies no charge, other than that which can be
levelled, in the same sense, against the most solid body of scientific
knowledge in the world. The fruitful question in each case alike is, how
far, if at all, does the hypothesis enable us to understand particular
facts.

The more careful of our scientific thinkers are well aware of the limits
under which they work and of the hypothetical character of their
results. "I take Euclidean space, and the existence of material
particles and elemental energy for granted," says the physicist; "deny
them, and I am helpless; grant them, and I shall establish quantitative
relations between the different forms of this elemental energy, and make
it tractable and tame to man's uses. All I teach depends upon my
hypothesis. In it is the secret of all the power I wield. I do not
pretend to say what this elemental energy is. I make no declaration
regarding the actual nature of things; and all questions as to the
ultimate origin or final destination of the world are beyond the scope
of my inquiry. I am ruled by my hypothesis; I regard phenomena _from my
point of view_; and my right to do so I substantiate by the practical
and theoretical results which follow." The language of geology,
chemistry, zoology, and even mathematics is the same. They all start
from a hypothesis; they are all based on an imaginative conception, and
in this sense their votaries are poets, who see the unity of being throb
in the particular fact.