But of course we cannot disabuse our minds of emotional and æsthetic perceptions; no human being can divest himself of such essential parts of his nature; and indeed it was even more in obedience to higher requirements than for the sake of mere sensuous richness that the musicians of the renaissance period so radically remodelled their art. The essence of their reforms is to be looked for, not in the increase of the first or sensuous value of music, but in the enhancement of its expressiveness, and of its plastic beauty. Expression, in general, may be defined as the presentation of a feeling or idea by means of an impression. The impression may act either directly, calling up the specific idea or feeling by virtue of a long-established association between them, or more generally, by simply inducing a state of mind congruous with the expression desired, and so tending to generate it. The former is the case in verbal expression (language), where certain definite symbols, words, are immemorially coupled in our minds with certain ideas, conceptions, or feelings, so that when we hear the word we immediately think the thing. Musical expression differs from verbal expression in that in does not act by this direct arbitrary symbolism, but rather by the more subtle general process which instills a feeling by setting up its appropriate atmosphere or _milieu_. It is much vaguer and more general, and for that very reason far more potent. The word “love,” for example, arbitrarily denotes a certain idea, not because it is anything like the idea, but because we all agree that that word is to mean that thing.[19] An amorous piece of music, on the contrary, utters no definite symbol; it makes our heart beat faster and deeper, it makes our blood circulate, it ravishes our senses and our minds, until whether we will or not we know what it says, though for our lives we could not put its burden into words. It is by this direct establishment in us of a congruous or favorable state of mind that the consonances of the mediæval music express religious peace; and it is no otherwise that dissonance, that powerful engine of the modern musician, expresses the inward division, the struggle and sweet torment, of idealistic states of feeling. The harshness, disagreeable in itself but essential to a process in which it is organically linked with sweetness and rest, arouses by an association of ideas a sense of the stern beauty, the tragic splendor, of the experience of the human heart. It reproduces in the sphere of sound that same series of states, that pain merging into joy, which we recognize in the sphere of our consciousness as so deeply characteristic of finite life. And so doing, it suggests or shadows forth the very essence of our nature, it echoes the utterance of our very hearts. It is no expurgated reading of the book of life: it is the full text, with all its shuddering horror and all its celestial joy.