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 admitted 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 theory was refuted by the same objection which destroyed aesthetic associationism in general: speech is unity, not multiplicity of images, and multiplicity does not explain, but presupposes the existence of the expression to explain. A variant of linguistic associationism is the imitative, that is to say, the theory of the onomatopoeia, which the same philologists deride under the name of the "bow-wow" theory, after the imitation of the dog's bark, which, according to the onomatopoeists, gives 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 onomatopes and conventions. This doctrine is altogether worthy of the scientific and philosophic decadence of the second half of the nineteenth century. [Sidenote] _Origin of language and its development._ We must here note a mistake into which have fallen those very philologists who have best penetrated the active nature of language. These, although they admit that language was _originally a spiritual creation_, yet maintain that it was largely increased later by _association_. But the distinction does not prevail, for origin in this case cannot mean anything but nature or essence. If, therefore, language be a spiritual creation, it will always be a creation; if it be association, it will have been so from the beginning. The mistake has arisen from not having grasped the general principle of Aesthetic, which we have noted: namely, that expressions already produced must redescend 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._