The names of natural bodies, animal, vegetable, or mineral, are of the second class; for they excite aggregates of sen sible ideas, and at the same time may be defined by an enumeration of their pro perties and characteristics. Thus like wise geometrical figures have both ideas and definitions. The definitions, in both cases, are so contrived as to leave out all the variable particularities of the ideas, and also to be more full and precise than the ideas generally are in the parts which are of a permanent nature.
Algebraic quantities, such as roots, powers, surds, &c. belong to the third class ; and have definitions only. The same may be said of scientifical terms of art, and of most abstract general terms, moral, metaphysical, and vulgar. How ever, mental emotions are apt to attend some of these even in passing slightly over the ear, and these emotions may be considered as ideas belonging to the re spective terms. Thus the very words, srratitude, mercy, cruelty, treachery, &c. separately taken, affect the mind ; and yet, since all reasoning upon them is to be founded on their definitions, it seems best to refer them to this third class.
Lastly, the particles, the, of, to, for, but, &c. have neither definition nor ideas, as we have limited those terms. _ 2. It will easily appear, from the oh• nervations here made upon words, and the associations which adhere to them, that the languages of different ages and nations must bear a great general resem blance to each other, and yet have con siderable particular differences ; whence any one may be translated into any other, so as to convey the same ideas in general, and yet not with perfect precision and exactness. They must resemble one another, because the phenomena of na ture which they are all intended to ex press, and the uses and exigencies of hu man life to which they minister, have a general resemblance. But then, as the bodily make and genius of each people, the air, soil, and climate, commerce, arts, sciences, religion, &c. make considerable differences in different ages and nations, it is natural to expect that the languages should have proportionable differences in respect of each other.
In learning a new language, the words. of it are at first substitutes for those of our native language ; that is, they are as sociated, by means of these, with the proper objects and ideas. When this
association is sufficiently strong, the mid dle bond is dropped, and the words of the new language become substitutes for, and suggest directly and immediately objects and ideas ; also clusters of other words in the same language.
In learning a new language, it is much easier to translate from it into the native one, than back again ; just as young chil dren are much better able to understand the expressions of others, than to express their own conceptions. And the reason is the same in both cases. Young chit= dren learn at first to go from the words of others, and those who learn a new lan guage, from the words of that language to the things signified. And the reverse of this, viz. to go from the things signified to the words, must be difficult for a time, from the nature of successive associations. It is to be added here, that the nature and connections of the things signified, often determine the import of sentences, though their grammatical analysis is not understood ; and that we suppose the person who attempts to translate from a new language, is sufficiently expert in passing from the things signified to the corresponding words of his own language. The power of association is every where conspicuous in these remarks.
3. It follows also from the foregoing reasoning, that persons who speak the same language cannot always mean the same things by the same words, but must sometimes mistake each other's meaning. This confusion and uncertainty arise from the different associations transferred upon the same words by the ffifference in the accidents and events of our lives. It is, however, much more common in discourses concerning abstract matters, where the terms stand fbr collections of other terms, sometimes at the pleasure of the speaker or writer, than in the com mon and necessary affairs of life ; for here frequent use, and the constancy of the phenomena of nature, intended to be expressed by words, have rendered their :,ease determinate and certain. However, it seems possible, and even not very diffi cult, for two truly candid and intelligent persons to understand each other upon any subject.