to the cause, and returning back from the cause, to form new inferences
concerning the effect, and examine the alterations, which it has
probably undergone, or may still undergo. But what is the foundation of
this method of reasoning? Plainly this; that man is a being, whom we
know by experience, whose motives and designs we are acquainted with,
and whose projects and inclinations have a certain connexion and
coherence, according to the laws which nature has established for the
government of such a creature. When, therefore, we find, that any work
has proceeded from the skill and industry of man; as we are otherwise
acquainted with the nature of the animal, we can draw a hundred
inferences concerning what may be expected from him; and these
inferences will all be founded in experience and observation. But did we
know man only from the single work or production which we examine, it
were impossible for us to argue in this manner; because our knowledge of
all the qualities, which we ascribe to him, being in that case derived
from the production, it is impossible they could point to anything
farther, or be the foundation of any new inference. The print of a foot
in the sand can only prove, when considered alone, that there was some
figure adapted to it, by which it was produced: but the print of a human
foot proves likewise, from our other experience, that there was probably
another foot, which also left its impression, though effaced by time or
other accidents. Here we mount from the effect to the cause; and
descending again from the cause, infer alterations in the effect; but
this is not a continuation of the same simple chain of reasoning. We
comprehend in this case a hundred other experiences and observations,
concerning the _usual_ figure and members of that species of animal,
without which this method of argument must be considered as fallacious
and sophistical.

113. The case is not the same with our reasonings from the works of