propositions to one, and, in this connection, is of interest to us merely as exhibiting one of the modes in which opinion is formed. It will be sufficient, therefore, to distinguish the term and the proposition as the two forms in which opinions, or the elements of opinions, are embodied. But the proposition is itself of two kinds, differing essentially in nature. In the one-if not an inference—it is simply the statement of a relation intuitively perceived to exist between two terms or names, that is to say, between the notions or concepts denoted by them,-as, e. g., where we say, Bodies are affected by gravity," or "Two islands cannot be contiguous," or "Fishes live in the sea, or "Man is rational"; in the other, it is a statement of a relation between terms, not intuitively perceived-or logically inferred-but assumed to be true from testimony or otherwise,―as, e. g., where we say, "Brutus was

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one of the murderers of Cæsar," or Hannibal was conquered by the Romans.” The former - in accordance with the definitions used throughout this work-will be called a judgment; the latter, an assumption. In the former case the truth of the proposition is involved in the meanings of the terms,-i. e., in the nature of the concepts or notions denoted by them; and this is true also of all inferences, or propositions inferred from judgments. So that with

relation to all such propositions, whether intuitively perceived or inferred, the original sources of opinion are the notions or concepts in which they are involved. We We may therefore distinguish, as the two sources of opinion afforded us by language, (1) the notions or concepts expressed in terms, and (2) assumptions, or assumed propositions.

With the truth of the latter, or the evidence on which they rest for credence, Logic is not concerned; nor is it concerned with them in any way, except as premises from which to argue; or to reject them as such, if they can be shown by logical processes to be false. But where such propositions are justified by experience, and come thus to be generally received, the result universally, or almost universally, is the generation of a new notion,-i. e., the notion of the relation perceived between its terms; which is either expressed in a new term or added to the content or meaning of an existing term; and this, indeed, to the extent it is attainable, is the end of science, and, in a perfect language, were such attainable,— would be the general result. Thus the general progress of human thought consists largely in the conversion of propositions into terms or names denoting the relations expressed in them; and hence, generally, in terms are contained many propositions, as, e. g., in " gravity, justice,"

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etc.-in the former of which is contained a large part of Physical Science, and in the latter nearly the whole theory of the State. In this way the stock of the common notions of mankind is continuously accumulated, until it may be said that the great part of all that has been achieved in thought by men is expressed or implied in terms or names. Here, therefore, are to be found the principal sources of opinion; and, compared with these, opinions embodied in propositions that cannot be, or have not been, reduced to single notions are limited in extent, and of secondary importance. And this is especially true with regard to the Moral Sciences; under which name I include all the various branches of the science of human nature; for in these sciences it is impossible to conceive of any rudimentary notion or thought that has not, in the long history of man, been conceived by the human mind and embodied in terms. With reference, therefore, to all that has been achieved in science or in popular thought, the sources of all our opinions, verified and unverified,-that is to say, of all our knowledge or supposed knowledge, are to be sought in language, and, principally, in the notions expressed in terms or or names'; and consequently, with reference to

If the reader will thoroughly apprehend this proposition, he will find in it the key, not only to Logic, but to all Phil

knowledge or supposed knowledge of this kind, our method must consist in the study of language.

85. RECEIVED OPINION DISTINGUISHED FROM TRUE KNOWLEDGE.-Our opinions, however, are derived from this source in two ways, which must be distinguished: namely, by tradition, by which our opinions are delivered to us ready made in the form of propositions,— and by reasoning upon the notions embodied in terms. For the thought contained in language is embodied in two ways, namely, explicitly, in the form of propositions, and implicitly, in terms; and of propositions,—as we have seen,-many are but explicit statements of what is implied in the notions osophy. The elements of knowledge, so far as already achieved, we repeat, are the notions or concepts incarnate in terms; and these must always constitute the principal source of our knowledge; for, in comparison with the knowledge thus expressed or implied, the original contributions of the most gifted of men to the common stock must be inconsiderable. Nor can any such contribution to the knowledge of mankind be regarded as completely achieved until embodied in definite terms; and hence the formation of such terms, or, what is the same, of the notions embodied in them, must be regarded as the end of scientific discovery. There is, therefore, nothing paradoxical in the assertion of Condillac that “Science is but language well made." Hence, to repeat what has been said, it is to the common stock of notions thus gradually accumulated by mankind and permanently secured by expression in terms, that we must resort as the principal source of all knowledge or science. See Appendix A.

expressed in terms, as, e. g., in the proposition, "All bodies are affected by gravity," etc. With reference to these, though they may be true, their mere reception cannot be said to constitute knowledge; but in the proper sense of the terms-we can know them only when we have reasoned them out for ourselves from the primary notions in which they are involved; as, e. g., in the Mathematics, where we cannot be said to have mastered a theorem until we are able to work it out from the premises by the exertion of our own powers unassisted by memory. With reference to all that has been achieved in thought, therefore, our method in the pursuit of knowledge must begin with the apprehension of the notions already formed by men and embodied in terms; and this involves the testing of those notions for ourselves by comparing them with the realities to which they are supposed to correspond.

§ 6. THE PHYSICAL AND MATHEMATICAL, DISTINGUISHED FROM THE MORAL SCIENCES.

- These observations apply equally to the Physical and Mathematical as to the Moral Sciences; but there are differences, partly essential and partly accidental, between the two classes of sciences, which must be adverted to ': (1) In the Physical Sciences and in the 1 See Appendix B.