to _must_, we introduce an idea
of necessity which most assuredly does not lie in the observed facts,
and has no warranty that I can discover elsewhere. For my part, I
utterly repudiate and anathematize the intruder. Fact I know; and Law I
know; but what is this Necessity, save an empty shadow of my own mind's
throwing?

But, if it is certain that we can have no knowledge of the nature of
either matter or spirit, and that the notion of necessity is something
illegitimately thrust into the perfectly legitimate conception of law,
the materialistic position that there is nothing in the world but
matter, force, and necessity, is as utterly devoid of justification as
the most baseless of theological dogmas. The fundamental doctrines of
materialism, like those of spiritualism, and most other "isms," lie
outside "the limits of philosophical inquiry," and David Hume's great
service to humanity is his irrefragable demonstration of what these
limits are. Hume called himself a sceptic, and therefore others cannot
be blamed if they apply the same title to him; but that does not alter
the fact that the name, with its existing implications, does him gross
injustice.

If a man asks me what the politics of the inhabitants of the moon are,
and I reply that I do not know; that neither I, nor any one else, have
any means of knowing; and that, under these circumstances, I decline to
trouble myself about the subject at all, I do not think he has any
right to call me a sceptic. On the contrary, in replying thus, I
conceive that I am simply honest and truthful, and show a proper regard
for the economy of time. So Hume's strong and subtle intellect takes up
a great many problems about which we are naturally curious, and shows us
that they are essentially questions of lunar politics, in their essence
incapable of being answered, and therefore not worth the attention of
men who have work to do in the world. And he thus ends one of his
essays:--

"If we take in hand any volume of Divinity, or school metaphysics,
for instance, let us ask, _Does it contain any abstract reasoning
concerning quantity or number_? No. _Does it contain any
experimental reasoning concerning matter of fact and existence_?
No. Commit it then to the flames; for it can contain nothing but
sophistry and illusion."[12]

Permit me to enforce this most wise advice. Why trouble ourselves about
matters of which, however important they may be, we