s, that theory must be just, although it may not be perfect,
as having comprehended every appearance; that is to say, a theory is
not perfect until it be founded upon every natural appearance; in which
case, those appearances will be explained by the theory. The theory of
gravitation, though no ways doubtful, was not so perfect before the
shape of this globe had been determined by actual measurement, and
before the direction of the plummet had been tried upon Shihallion, as
after those observations had been made. But a theory which should be
merely hypothetical, or founded upon a few appearances, can only be
received as a theory, after it has been found to correspond properly
with nature; it would then be held a proper explanation of those natural
appearances with which it corresponded; and, the more of those phenomena
that were thus explained by the theory, the more would that, which had
been first conjectural, be converted into a theory legitimately founded
upon natural appearances.

Matter of fact is that upon which science proceeds, by generalization,
to form theory, for the purpose of philosophy, or the knowledge of all
natural causes; and it is by the companion of these matters of fact with
any theory, that such a theory will be tried. But, in judging of matter
of fact, let us be cautious of deceiving ourselves, by substituting
speculative reasoning in place of actual events.

Nature, as the subject of our observation, consists of two sorts of
objects; for, things are either active, when we perceive change to take
place in consequence of such action, or they are quiescent, when we
perceive no change to take place. Now, it is evident, that in judging
of the active powers of nature from the quiescent objects of our
information, we are liable to error, in misinterpreting the objects
which we see; we thus form to ourselves false or erroneous opinion
concerning the general laws of action, and the powers of nature. In
comparing, therefore, generalised facts, or theory, with particular
observations, there is required the greatest care, neither, on the one
hand, to strain the appearances, so as to bring in to the theory a fact
belonging to another class of things; nor, on the other, to condemn a
proper theory, merely because that theory has not been extended to the
explanation of every natural appearance.

But, besides the misinterpretation of matters of fact, we are also to
guard against the misrepresentation of natura