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 which all advances in science are carried on; and scientific persons are in general aware, that it is and must be so. However, I thought it not improper to illustrate this general process by a parallel taken from algebra, in which there is great exactness and beauty. Besides, writers do not often dispose their arguments and approximations in this way, though for want of it they lose much of their clearness and force; and, where the writer does this, the reader is frequently apt to overlook the order of proofs and positions.

Sir Isaac Newton’s Optics, Chronology, and Comment on Daniel, abound with instances to this purpose: and it is probable, that his great abilities and practice in algebraic investigations led him to it insensibly. In his Chronology he first shews in gross, that the technical chronology of the ancient Greeks led them to carry their authorities higher than the truth; and then, that the time of the Sesostris mentioned by the Greek historians was near that of Sesac mentioned in the Old Testament; whence it follows, that these two persons were the same; and consequently, that the exact time of Sesostris’s expedition may now be fixed by the Old Testament. And now, having two points absolutely fixed, viz. the expeditions of Sesostris and Xerxes, he fixes all the most remarkable intermediate events; and these being also fixed, he goes on to the less remarkable ones in the Greek history. And the chronology of the Greeks being rectified, he makes use of it to rectify the cotemporary affairs of the Egyptians, Assyrians, Babylonians, Medes, and Persians, making use of the preceding step every where, for the determination of the subsequent one. He does also, in many cases, cast light and evidence back from the subsequent ones upon the precedent. But the other is his own order of proof, and ought to be that in which those who call his chronology in question should proceed to inquire into it.

The fourth and last method is that used by decypherers, in investigating words written in unknown characters, or in known ones substituted for one another, according to secret and complex laws. The particular methods by which this is done are only known to those who study and practise this art: however, it is manifest in general, that it is an algebra of its own kind, and that it bears a great resemblance to the three foregoing methods; also, that it may be said, with justness and propriety in general, that philosophy is the art of decyphering the mysteries of nature; that criticism bears an obvious relation to decyphering; and that every theory which can explain all the phænomena, has all the same evidence in its favour, that it is possible the key of a cypher can have from its explaining that cypher. And if the cause assigned by the theory have also its real existence proved, it may be compared to the explanation of a cypher; which may be verified by the evidence of the person who writes in that cypher.

These speculations may seem uncouth to those who are not