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Thomas Chater Eng

with best wishes from
Charles Opence

Extribuerfa 22 : October 1823.

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PRINTED FOR WAUGH & INNES, EDINBURGH;

AND OGLE, DUNCAN & CO. LONDON.

1821.

L

BT1101
27

27751

004

OF THE

LIBRAT
UNIVERS

CAT

INTRODUCTORY CHAPTER.

THERE is a principle in our nature which makes us dissatisfied with unexplained and unconnected facts; which leads us to theorize all the particulars of our knowledge, or to form in our minds some system of causes sufficient to explain or produce the effects which we see; and which teaches us to believe or disbelieve in the truth of any system which may be presented to us, just as it appears adequate or inadequate to afford that explanation of which we are in pursuit. We have an intuitive perception that the appearances of Nature are connected by the relation of cause and effect; and we have also an instinctive desire to classify and arrange the seemingly confused mass of

B

man.

facts with which we are surrounded, according to this distinguishing relationship. From these principles have proceeded all the theories which were ever formed by But these principles alone can never make a true theory: They teach us to theorize; but experience is necessary in order to theorize justly. We must be acquainted with the ordinary operation of causes, before we can combine them into a theory which will satisfy the mind. But when we are convinced of the real existence of a cause in Nature, and when we find that a class of a physical facts is explained by the supposition of this cause, and tallies exactly with its ordinary operation, we resist both reason and instinct when we resist the conviction that this class of facts does result from this cause. On this process of reasoning is grounded our conviction, that the various phenomena of the heavenly bodies are results from the principle or law of gravitation. That great master of theories, Adam Smith, has given a most appropriate and beautiful illustration of this process, in his "History of Astronomy." He has there shown, how the speculative system was always accom

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