seduced us into the
present digression.

It is, no doubt, perfectly true, that we all believe in the existence
of matter, and that we all act up to this belief. But surely that
statement is not a thing, to be put into a book and _sold_. It is not
even a thing which one man is entitled to tell _gratuitously_ to another
man who knows it just as well as he does. It must be admitted upon a
moment's reflection, that to communicate such information is to trifle
with people's patience in an intolerable degree, is to trespass most
abominably upon public or upon private indulgence. What, then, shall we
say, when we find this kind of truth not only gravely imparted, but
vehemently reiterated and enforced by scientific men, as it is in the
pages of Dr Reid and other celebrated expounders of the philosophy of
the human mind? We shall only say, that the economy of science is less
understood than that of commerce; and that while material articles, such
as air and sunshine, which are accessible to all, are for that reason
excluded from the market of trade, many intellectual wares, which are at
least equally accessible, are most preposterously permitted to have a
place in the market of science. Such wares are the instinctive
principles of Dr Reid. To inform a man that the material universe
exists, and that he believes in its existence, is to take for granted
that he is an idiot.

The circumstance which led the philosophers of Common Sense to traffic
in this kind of article, was perhaps the notion that truths had a value
in communication in proportion to their _importance_ to mankind. But
that is a most mistaken idea. The most important truths have absolutely
no value in communication. The truth that "each of us exists"--the truth
"that each of us is the same person to-day that he was yesterday," the
truth that "a material universe exists, and that we believe in its
existence,"--all these are most important truths--most important things
to know. It is difficult to see how we could get on without this
knowledge. Yet they are not worth one straw in communication. And why
not? Just for the same reason that atmospheric air, though absolutely
indispensable to our existence, has no value whatever in exchange--this
reason being that we can get, and have already got, both the air and the
truths, in unlimited abundance for nothing,--and thanks to no man. Why
_give_ a man what he has already _got_ to his heart's content--why
_teach_ him what h