Linguistic expression, or speech, has often seemed to be a fact of _interjection,_ which belongs to the so-called physical expressions of the feelings, common alike to men and animals. But it was soon perceived that an abyss yawns between the "Ah!" which is a physical reflex of pain and a word; as also between that "Ah!" of pain and the "Ah!" employed as a word. The theory of the interjection being abandoned (jocosely termed the "Ah! Ah!" theory by German linguists), the theory of _association_ or _convention_ appeared. This is liable to the same objection which destroyed æsthetic associationism in general: speech is unity, not multiplicity of images, and multiplicity does not explain, but indeed presupposes the expression to be explained. A variant of linguistic associationism is the imitative, that is to say, the theory of _onomatopœia,_ which the same philologists deride under the name of the "bow-wow" theory, from the imitation of the dog's bark, which, according to the onomatopœists, must have given its name to the dog. The most usual theory of our times as regards language (apart from mere crass naturalism) consists of a sort of eclecticism or mixture of the various theories to which we have referred. It is assumed that language is in part the product of interjections and in part of onomatopœia and convention. This doctrine is altogether worthy of the philosophical decadence of the second half of the nineteenth century. [Sidenote: _Origin of language and its development._] We must here note an error into which have fallen those very philologists who have best discerned the activistic nature of language, when they maintain that although language was _originally a spiritual creation,_ yet that it afterwards increased by _association._ But the distinction does not hold, for origin in this case cannot mean anything but nature or character; and if language be spiritual creation, it must always be creation; if it be association, it must have been so from the beginning. The error has arisen from having failed to grasp the general principle of Æsthetic, known to us: that expressions already produced must descend to the rank of impressions before they can give rise to new impressions. When we utter new words we generally transform the old ones, varying or enlarging their meaning; but this process is not associative, it is _creative,_ although the creation has for material the impressions, not of the hypothetical primitive man, but of man who has lived long ages in society, and who has, so to say, stored so many things in his psychic organism, and among them so much language. [Sidenote: _Relation between Grammar and Logic._]