All speech is compounded of two elements, the words and the tones in which they are uttered—­the signs of ideas and the signs of feelings.  While certain articulations express the thought, certain vocal sounds express the more or less of pain or pleasure which the thought gives.  Using the word cadence in an unusually extended sense, as comprehending all modifications of voice, we may say that cadence is the commentary of the emotions upon the propositions of the intellect.  The duality of spoken language, though not formally recognised, is recognised in practice by every one; and every one knows that very often more weight attaches to the tones than to the words.  Daily experience supplies cases in which the same sentence of disapproval will be understood as meaning little or meaning much, according to the inflections of voice which accompany it; and daily experience supplies still more striking cases in which words and tones are in direct contradiction—­the first expressing consent, while the last express reluctance; and the last being believed rather than the first.

These two distinct but interwoven elements of speech have been undergoing a simultaneous development.  We know that in the course of civilisation words have been multiplied, new parts of speech have been introduced, sentences have grown more varied and complex; and we may fairly infer that during the same time new modifications of voice have come into use, fresh intervals have been adopted, and cadences have become more elaborate.  For while, on the one hand, it is absurd to suppose that, along with the undeveloped verbal forms of barbarism, there existed a developed system of vocal inflections; it is, on the other hand, necessary to suppose that, along with the higher and more numerous verbal forms needed to convey the multiplied and complicated ideas of civilised life, there have grown up those more involved changes of voice which express the feelings proper to such ideas.  If intellectual language is a growth, so also, without doubt, is emotional language a growth.

Now, the hypothesis which we have hinted above, is, that beyond the direct pleasure which it gives, music has the indirect effect of developing this language of the emotions.  Having its root, as we have endeavoured to show, in those tones, intervals, and cadences of speech which express feeling—­arising by the combination and intensifying of these, and coming finally to have an embodiment of its own—­music has all along been reacting upon speech, and increasing its power of rendering emotion.  The use in recitative and song of inflections more expressive than ordinary ones, must from the beginning have tended to develop the ordinary ones.  Familiarity with the more varied combinations of tones that occur in vocal music can scarcely have failed to give greater variety of combination to the tones in which we utter our impressions and desires.  The complex musical phrases by which composers have conveyed complex emotions, may rationally be supposed to have influenced us in making those involved cadences of conversation by which we convey our subtler thoughts and feelings.