The first class of natural signs comprehends those
whose connection with the thing signified is established
by nature, but discovered only by experience. The
whole of genuine philosophy consists in discovering such
connections, and reducing them to general rules. The
great Lord Verulam had a perfect comprehension of
this, when he called it an interpretation of nature. No
man ever more distinctly understood or happily ex-
pressed the nature and foundation of the philosophic
art. What is all we know of mechanics, astronomy, and
optics, but connections established by nature, and dis-
covered by experience or observation, and consequences
deduced from them ? All the knowledge we have in agri-
culture, gardening, chemistry, and medicine, is built
upon the same foundation. And if ever our philosophy
concerning the human mind is carried so far as to de-
serve the name of science, which ought never to be de-
spaired of, it must be by observing facts, reducing them
to general rules, and drawing just conclusions from them.
What we commonly call natural causes might, with morQ



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Sbc.hi:] the philosophy of reid. 137

propriety, be called natural signs, and what we call
effects, the things signified. The causes have no proper
efficiency or causality, as far as we know: and all we can
certainly affirm is, that nature hath established a con-
stant conjunction between them and the things called
their effects; and hath given to mankind a disposition
to observe those connections, to confide in their contin-
uance, and to make use of them for the improvement of
our knowledge, and increase of our power.
