Far otherwise do we interpret the story of the world. Inspired by the great doctrine of the nineteenth century, the doctrine of evolution, first formulated by biology, but immediately applied to all realms of knowledge, we read in events a continuous movement, a coherent growth, a gradual, vast, and single process. For us, individual events and men sink into insignificance in comparison with the great drama of which they are only acts and actors. For us, great popular movements, instinctive strivings, of which the men and women under their sway were unconscious, vast blossomings of vital energy the roots of which were far below the surface of the human mind, rise into relief as the true interests of the historian, and we interpret all particular happenings and special persons in the light of these universal tendencies. In geology we trace the continuous formation of the earth through innumerable years; in zoology we study those slow but constant transformations of animals which are effected by natural selection and the survival of the fittest; in sociology we examine the painful yet inevitable crystallization out of the human spirit of such ideas as responsibility, liberty, justice; in philosophy we learn of the subtle implications of our nature, and so learning, substitute a human God for the idols of savages and the remote tyrannical deities of half-developed religions. There is not a branch of our thought in which this way of interpreting life as a process, this conceiving of it as dynamic and vital rather than static and inert, has not enlarged our outlook, deepened our sense of the sacredness and wonder of the universe, and filled our spirits with a new freedom, enthusiasm, and hope.

Peculiarly interesting is the application of this mode of study to the art of music. The expression of feeling through sounds combined in beautiful forms, gives us an opportunity, as cannot be too often pointed out, [1] for a much freer and more self-determined activity than we can enjoy in our other artistic pursuits. Because the art of music, both in its material and in its content, is less shackled, less thwarted in its characteristic processes, than the representative arts, its evolution is remarkably obvious and easy to trace. Its material, in the first place, is a product of man’s free selection; that complex system of musical tones which he has constructed by many centuries of work, is his own, to use as he will, in a sense in which language, natural objects, and physical substances can never be. Whereas the growth of poetry, of painting, of sculpture, of architecture, is complicated and distorted by a thousand external conditions, that of music is determined by its own inner laws alone,—by the laws, that is to say, of sound-production, of sound-perception, and of psychology. In the second place, the content of music, that which it expresses by means of these freely selected and composed tones, is purely internal. It is easy to see that the objects of musical expression, namely, human emotions in their essence, reduced, so to speak, to their lowest terms, are more fluid to manipulation than the comparatively fixed, indocile, and external objects of the representative arts. By virtue, then, both of its material medium and of its ideal content, music enjoys, among human modes of expression, a unique freedom and autonomy. It grows, not under pressure from outside, but by its own inner vitality; its forms are determined, not by correspondence with anything in the heavens or on the earth, but, like those of the snow-crystals, by the inexorable laws that govern it; and the particular changes it undergoes in its evolution, marking merely successive incarnations of tendencies and potencies always implicit in it, can be traced with comparative ease, clearness, and certainty.

But however unmistakably musical history may reveal an evolutionary process, it does not reveal that process as perfectly regular and uniform. That general tendency from a low toward a high state of organization, with increase in definiteness, coherence, and heterogeneity, which readers of Herbert Spencer expect in any evolutionary series, does characterize the growth of music as a whole; but within the large general process we also observe, as we do in many other cases of evolution of any degree of complexity, many momentary phases sharply marked off from one another, many separate and distinct periods, like the chapters in a book or the acts in a play. Each period, beginning tentatively, maturing slowly, and culminating in music which carries its characteristic effects to the highest possible pitch, is succeeded by another, presenting the same phases of growth, but seeking effects quite different. All the periods hang together in a large view; yet they are, after all, diverse in character, and therefore capable of being distinguished, and even dated.

An analogy offered by certain well-known chemical processes may help to make comprehensible this periodic nature of musical evolution. Chemists have a term, “critical point,” by which they name a stage in the behavior of a substance, under some systematic treatment, at which it suddenly undergoes some striking change, some catastrophic transformation. Put, for example, a lump of ice in a crucible and apply an even heat by which its temperature is raised, say, one degree each minute. Here is a systematic treatment of the ice, a steady influence exerted upon it. Yet, curiously enough, this ice which is being so equably acted upon will not change its form in the equable, regular fashion we might expect. It will seem to undergo little or no change until, at a given moment, suddenly, it passes into water, a liquid wholly different in appearance from the original solid. It has reached a “critical point.” Continue the heating, and presently another critical point will be reached, at which, with equal suddenness, the liquid will be transformed into a vapor—steam. These catastrophes, in which the physical properties of the substance suddenly change, are conditioned, of course, by its chemical nature. They take place in the midst of a systematic treatment which we might expect to produce only gradual, inconspicuous effects, but which, as a matter of fact, produces a series of events as strikingly differentiated one from another as the acts of a drama.

It is in a similar way that, in the history of music, the tonal material used, under the systematic treatment of man’s æsthetic faculty, has been constrained by its nature to undergo sudden changes, to recrystallize in novel ways, to take on unwonted aspects which initiate new periods. When the possibilities of one sort of tone-combination are nearly or quite exhausted, the keener minds of a generation, led by groping but unerring instinct, grasp an unused principle of organization, latent in the material, and inaugurate a new style. This in turn runs its course, develops its resources, reaches its perfection, and is succeeded by another, which, after due time, is also superseded. All these periods are but moments in one vast evolution, successive blossomings from the one root of human feeling expressible in music; yet each has its individual qualities, its peculiar style, its special masters. It is possible both to trace certain general tendencies through them all, and to define other special qualities in which each is peculiar; and it will be worth while, before passing on to our proposed study of the particular period of Beethoven, to describe thus in general terms the salient features of the evolution as a whole, and to characterize, however briefly, the individual periods we can discriminate in it.

In the most general point of view, an evolution, of whatever sort, is a progress from what Spencer calls “indefinite, incoherent, homogeneity,” to what, consistently if rather overwhelmingly, he calls “definite, coherent, heterogeneity.” All low forms of life, that is to say, are so homogeneous in constitution as to be comparatively indefinite and incoherent; their parts, being all very much alike, cannot be built up into definite, strongly cohesive structures. A jelly fish, made up of thousands of but slightly differentiated cells, and without legs, arms, head, or any viscera worth mentioning except stomach, is doubtless a useful animal, but not one of pronounced individuality or solidarity. A savage tribe, consisting of many human beings almost indistinguishable from one another as regards character, strength, accomplishments, or powers of leadership, is a similar phenomenon in a different field, a sort of social jelly fish.

In higher forms of life, on the contrary, such as vertebrate animals and civilized communities, the elementary parts are sufficiently diverse to be interwoven into highly individual and compact organisms. The variety of the atoms or molecules makes possible a great solidarity in the molar unit they compose, since the uniqueness and indissolubility of a structure is directly proportionate to the diversity of the elements that compose it. A man, if he is to attain the dignity of manhood, must be more than a stomach; he must knit into his single unity a bony skeleton, a circulatory system, a brain and nervous apparatus, complicated viscera, and heart, mind, and spirit. A state depends for its vitality on the varied characters and abilities of its citizens; it must have laborers, artisans, merchants, sailors, soldiers, students, and statesmen. In the second book of his “Republic,” Plato describes the differentiation of talents and pursuits in the citizens on which depends the advance in civilization of the society. Such an increase in differentiation of the parts, accompanied by increasing definiteness and coherence in the wholes, characterizes every process of evolution.

The history of music is the history of such an evolution. Music began with vague, unlocated sounds, not combined with one another, but following at haphazard, and but slightly contrasted in pitch or duration. Gradually, under the inconceivably slow yet irresistible influence of men’s selective and constructive faculty, these sounds took on definiteness, were fixed in pitch, were measured in time, were knit into phrases and themes as words are knit into sentences, were combined simultaneously in chords as individuals are combined in communities;—became, in a word, the various, clearly defined, and highly organized family of tones we use in modern music. Two passages from Spencer’s “First Principles” will bring before us very clearly the advance music has made towards heterogeneity in its elements, on the one hand, and towards definiteness and coherence in its wholes, on the other. “It needs,” he says, “but to contrast music as it is with music as it was, to see how immense is the increase of heterogeneity. We see this ... on comparing any one sample of aboriginal music with a sample of modern music—even an ordinary song for the piano; which we find to be relatively highly heterogeneous, not only in respect of the varieties in the pitch and in the length of the notes, the number of different notes sounding at the same instant in company with the voice, and the variations of strength with which they are sounded and sung, but in respect of the changes of key, the changes of time, the changes of timbre of the voice, and the many other modifications of expression: while between the old monotonous dance-chant and a grand opera of our own day, with its endless orchestral complexities and vocal combinations, the contrast in heterogeneity is so extreme that it seems scarcely credible that the one should have been the ancestor of the other.”[2] Of the corresponding increase in coherence and definiteness he writes as follows: “In music, progressive integration is displayed in numerous ways. The simple cadence embracing but a few notes, which in the chants of savages is monotonously repeated, becomes, among civilized races, a long series of different musical phrases combined into one whole; and so complete is the integration, that the melody cannot be broken off in the middle, nor shorn of its final note, without giving us a painful sense of incompleteness. When to the air, a bass, a tenor, and an alto are added; and when to the harmony of different voice-parts there is added an accompaniment; we see exemplified integrations of another order, which grow gradually more elaborate. And the process is carried a stage higher when these complex solos, concerted pieces, choruses, and orchestral effects, are combined into the vast ensemble of a musical drama; of which, be it remembered, the artistic perfection largely consists in the subordination of the particular effects to the total effect.”[3] In innumerable ways, which these passages will perhaps suffice to suggest, the material of music has undergone a continuous, orderly, and progressive process of development, from its earliest days down to our own. It has exemplified, in short, an evolution from “indefinite, incoherent, homogeneity” to “definite, coherent, heterogeneity.”

Concomitantly with this special evolution of the sound-material of music, moreover, has gone on a more general evolution of human faculties, which has involved a gradual turning away of men’s attention from comparatively low forms of musical effect to those higher forms which require for their appreciation a good deal of concentration, perception, and power of intellectual synthesis. What was the exclusive concern of the earliest musicians became, as time went on, but a factor in a more complex artistic enjoyment. In order to understand this aspect of the matter clearly, we shall have to distinguish as accurately as possible three kinds of musical effect, all indispensable to music worthy of the name, yet not of equal dignity and value.