Language has sometimes been looked upon as an act of volition or of choice. But others have discovered the impossibility of creating language artificially, by an act of will. _Tu, Caesar, civitatem dare potes homini, verbo non poles!_ was once said to the Roman Emperor. The aesthetic (and therefore theoretic) nature of expression supplies the method of correcting the scientific error which lies in the conception of a (normative) _Grammar_, containing the rules of speaking well. Good sense has always rebelled against this error. An example of such rebellion is the "So much the worse for grammar" of Voltaire. But the impossibility of a normative grammar is also recognized by those who teach it, when they confess that to write well cannot be learned by rules, that there are no rules without exceptions, and that the study of Grammar should be conducted practically, by reading and by examples, which form the literary taste. The scientific reason of this impossibility lies in what we have already proved: that a technique of the theoretical amounts to a contradiction in terms. And what could a (normative) grammar be, but just a technique of linguistic expression, that is to say, of a theoretic fact? [Sidenote] _Didactic purposes._ The case in which Grammar is understood merely as an empirical discipline, that is to say, as a collection of groups useful for learning languages, without any claim whatever to philosophic truth, is quite different. Even the abstractions of the parts of speech are in this case both admissible and of assistance. Many books entitled treatises of Linguistic have a merely didactic purpose; they are simply scholastic manuals. We find in them, in truth, a little of everything, from the description of the vocal apparatus and of the artificial machines (phonographs) which can imitate it, to summaries of the most important results obtained by Indo-European, Semitic, Coptic, Chinese, or other philologies; from philosophic generalizations on the origin or nature of language, to advice on calligraphy, and the arrangement of schedules for philological spoils. But this mass of notions, which is here taught in a fragmentary and incomplete manner as regards the language in its essence, the language as expression, resolves itself into notions of Aesthetic. Nothing exists outside _Aesthetic_, which gives knowledge of the nature of language, and _empirical Grammar_, which is a pedagogic expedient, save the _History of languages_ in their living reality, that is, the history of concrete literary productions, which is substantially identical with the _History of literature_. [Sidenote] _Elementary linguistic facts or roots._