Several writers of eminence have attempted to explain the origin, progress and structure of languages, and have handled the subject with great ingenuity and profound learning; as Harris, Smith, Beatie, Blair, Condillac, and others. But the discovery of the true theory of the construction of language, seems to have been reserved for Mr. Horne Tooke, author of the "Diversions of Purley." In this treatise, however exceptionable may be particular instances of the writer's spirit and manner, the principles on which the formation of languages depends, are unfolded and demonstrated by an etymological analysis of the Saxon or Gothic origin of the English particles. From the proofs which this writer produces, and from various other circumstances, it appears probable, that the _noun_ or substantive is the principal part of speech, and from which most words are originally derived. The invention and progress of articulate sounds must have been extremely slow. Rude savages have originally no method of conveying ideas, but by looks, signs, and those inarticulate sounds, called by grammarians, _Interjections_. These are probably the first beginnings of language. They are produced by the passions, and are perhaps very little superior, in point of articulation or significancy, to the sounds which express the wants of the brutes.[85] But the first sounds, which, by being often repeated, would become articulate, would be those which savages use to convey their ideas of certain visible objects, which first employ their attention. These sounds, by constant application to the same things, would gradually become the _names_ of those objects, and thus acquire a permanent signification. In this manner, rivers, mountains, trees, and such animals as afford food for savages, would first acquire names; and next to them, such other objects as can be noticed or perceived by the senses. Those names which are given to ideas called _abstract_ and _complex_, or, to speak more correctly, those names which express a combination of ideas, are invented much later in the progress of language. Such are the words, faith, hope, virtue, genius, &c. It is unnecessary, and perhaps impossible, to describe the whole process of the formation of languages; but we may reason from the nature of things that the _necessary_ parts of speech would be the first formed; and it is very evident from etymology that all the others are derived from these, either by abbreviation or combination. The necessary parts of speech are the _noun_ and _verb_; and perhaps we may add the _article_. Pronouns are not necessary, but from their utility, must be a very early invention.