. Huxley, too) to his philosophy; and he would have
escaped materialism more effectively, if he had remained faithful to his
theory of evolution. It is a disloyalty, not only to science, but to
thought, to cast away our categories when they seem to imply
inconvenient consequences. They must be valid universally, if they are
valid at all.

Mr. Tyndall contends that nature makes man, and he finds evidence in the
fact that we eat and drink, "of the control of mind by matter." Now, it
seems to me, that _if_ nature makes man, then nature makes man's
thoughts also. His sensations, feelings, ideas, notions, being those of
a naturally-evolved agent, are revelations of the potency of the primal
matter, just as truly as are the buds, flowers, and fruits of a tree. No
doubt, we cannot as yet "comprehend the connection" between nervous
action and sensation, any more than we can comprehend the connection
between inorganic and organic existence. But, if the absence of
"experimental evidence" does not disprove the hypothesis in the one
case, it can not disprove it in the other. There are two crucial points
in which the theory has not been established.

But, in both cases alike, there is the same kind of evidence that the
connection exists; although in neither case can we, as yet, discover
what it is. Plants live by changing inorganic elements into organic
structure; and man is intelligent only in so far as he crosses over the
boundary between subject and object, and knows the world without him.
There is no "impassable gulf separating the subject and object"; if
there were we could not know anything of either. There are not two
worlds--the one of thoughts, the other of things--which are absolutely
exclusive of each other, but one universe in which thought and reality
meet. Mr. Tyndall thinks that it is an inference (and an inference over
an impassable gulf!) that anything answering to our impressions exists
outside ourselves. "The question of the external world is the great
battleground of metaphysics," he quotes approvingly from Mr. J.S. Mill.
But the question of the external world is not whether that world exists;
it is, how are we to account for our knowledge that it does exist. The
inference is not from thoughts to things, nor from things to thoughts,
but from a partially known world to a systematic theory of that world.
Philosophy is not engaged on the foolish enterprise of trying to
discover whether the world exists, or whether