(ββ) With regard to these means as such we have already above formed our conception of the timbre proper to them in the sense that it is the result of a vibration of the spatial medium, is the first excitation thereof of ideal import, which enforces itself as such in contradistinction to the purely sensuous juxtaposition, and, by virtue of this negation of spatial reality, asserts itself as the ideal unity of all the physical qualities of specific gravity and the purely sensuous type of corporeal coalescence. If we inquire further as to the qualitative peculiarities of the medium thus made to emit musical sound we shall find that in its character as material substance no less than as artificially constructed, it varies greatly. We may have a longitudinal or oscillating[442] column of air, which is limited by a fixed channel of wood or metal, or we may have a longitudinally stretched string of gut or metal, or in other cases a stretched surface of parchment or a bell of glass or metal. In this connection we may draw attention to the following distinguishing features. In the first place it is the lineal direction[443] which is mainly predominant, and produces the instruments most effective in musical employment; and this is so whether, as in the case of wind-instruments, the main principle is represented by a column of air which is relatively more deficient in cohesion or by a material line adapted to tension, but of sufficient elasticity to be made to vibrate, as is the case with stringed instruments.
Secondly, we have the principle of surface rather than line represented in instruments of inferior significance, such as the kettle-drum, bell, and harmonica. There is, in fact, a subtle sympathy between the self-audible principle of ideality and that type of rectilinear tone[444], which, by virtue of its essentially simple subjectivity, demands the resonant vibration of simple line extension rather than that of the broad and round surface. In other words, ideality is as subject this spiritual point, which is made audible in tone as its mode of expression. But the closest approach to the exposition and expression of the mere punctum is not the surface, but the simple linear direction. From this point of view broad or round surfaces are not adapted to the requirements and enforcement of such audibility. In the case of the kettle-drum we have a skin stretched over a kettle or basin, which by being struck at a single point sets the entire surface vibrating with a muffled sound. Though a musical sound, it is one which from its very nature, as belonging to such an instrument, it is impossible to bring either to clear definition or any considerable degree of variety. We find a difficulty of an opposite type in the case of the harmonica and the bells of glass which are set in vibration in it. In this case it is the concentrated intensity of tone which fails to project itself, and which is of such an affecting character that not a few, when hearing it, receive actual nervous pain. But, despite this specific effect, this instrument is unable to give permanent pleasure and is with difficulty combined with other instruments on the rare occasions such an attempt is made. We find the same defect on the side of differentiation of tone in the bell and a similar punctually repeated stroke as in the case of the kettle-drum. The ring of a bell, however, is not so muffled as in the latter; it rings out clearly, although its persistent reverberation is more the mere echo of the single beat as struck at regular intervals.
Thirdly, the human voice may be regarded in respect to the tones emitted as the most complete instrument of all. It unites in itself the characteristics of both the wind instrument and the string. That is to say we have here in one aspect of it a column of air which vibrates, and, further, by virtue of the muscles, the principle of a string under tension. Just as we saw in the case of the colour inherent in the human skin, we had what was in its aspect of ideal unity, the most essentially perfect presentment of colour, so, too, we may affirm of the human voice that it contains the ideal compass of sound, all that in other instruments is differentiated in its several composite parts. We have here the perfect tone, which is capable of blending in the most facile and beautiful way with all other instruments. Add to this that the human voice is to be apprehended as the essential tone of the soul itself, as the concordant sound which by virtue of its nature expresses the ideal character of the inner life, and most immediately directs such expression. In the case of all other instruments on the contrary we find that a material thing is set in vibration, which, in the use that is made of it, is placed in a relation of indifference to and outside of the soul and its emotion. In the human song, however, it is the human body itself from which the soul breaks into utterance. For this reason, too, the human voice is unfolded, in accord with the subjective temperament and emotion, in a vast manifold of particularity. And this variety, if we consider its distinguishing features sufficiently generalized, is based on national or other natural relations. Thus, for example, we find that the Italians are pre-eminently the people among whom we meet with the most beautiful voices. An important feature of this beauty is to start with the content of the sound simply as sound, its pure metallic quality, which neither fines away in mere keenness or vitreous attenuation, nor maintains a persistent muffled and hollow character, but, at the same time, though never carried to the point of tremolo in its tone, preserves in the compact body of its tone something of the vital vibration of the soul itself. Above all else the purity of voice-production is most essential, or in other words we must have no foreign element of sound asserted alongside of the freest expression of essential tone.
(γγ) Such a totality of instruments the art of music can employ, either in separation or complete combination. In the latter case of late years we may note an exceptional artistic development. The difficulty of such artistic collaboration is enormous. Every instrument possesses a character of its own, which is not directly congenial to the peculiarity of some other instrument. It follows from this that whether we are considering the harmonious co-operation of various instruments of different type, or the effective production of some particular quality of sound such as that of wind or strings, or the sudden blast of trombones, or the successive alternations of change that are inseparable from the music of a large choir, in all such cases knowledge, circumspection, experience, and imaginative endowment are indispensable, in order that, in every example of the kind, whether of tonal quality, transition, opposition, progression, or mediation, we do not lose sight of an ideal significance, the soul and emotional value of the music. For example, I find in the symphonies of Mozart, who was a great master of instrumentation and its sense-appealing, that is its vital no less than luminous variety, a sort of alternation between the different instruments which frequently resembles in its dramatic interplay a kind of dialogue. In one aspect of this the character of some particular type of instrument is carried to a point, which anticipates and prepares the way for that of another; looked at in another way, one kind of instrument replies to another; or asserts some typical mode of expression which is denied to the instrument it follows, so that in the most graceful fashion we thus get a kind of conversation of appeal and response, which has its beginning, advance and consummation.
(β) The second material which enlists our attention is no longer the physical quality asserted in the sound, but the essential definition of the tone itself, and its relation to other tones. This objective relation, whereby musical tone in the first instance, not merely in its essential and emphatically defined singularity, but also in its fundamental relation to simultaneously persistent tones, expatiates, constitutes the actual harmonious element of music, and is based, regarded under its own original physical conditions, upon quantitative differences and numerical proportions. A closer examination of the contents of this system of harmony presents, as understood to-day, the following points of importance.
First, we have separate tones in their definite metrical relation, and associated with other tones. This is the theory of particular intervals.
Secondly, there is the connected series of tones or notes in their simplest form of succession, in which one tone immediately leads up to another; such are the scales.
Thirdly, we have the distinctive characteristics of these scales, which, in so far as each starts from a different tone, as its fundamental tone, is thereby differentiated into the particular keys distinct from each other, and into the system of keys which they constitute.
(αα) The particular notes do not only receive their tone, but also the more inclusively positive[445] determination of such sound by virtue of a corporeal substance in vibration. In order to get at this determinacy we have to define the type of vibration itself not in any chance or capricious manner, but once for all as it essentially is. The column of air, for example, or the string or surface under tension, which produces sound possesses invariably a certain length or extension. If we take a string, for instance, and fasten it between two points, and set the part of it thus stretched in vibration, the points of initial importance to discover are the thickness of the string, and the degree of tension. If we have these two aspects identical in the case of two strings then the all-important question follows, as was first noticed by Pythagoras, what is the string's length, the reason being that strings, in other respects identical, if of different lengths give a different number of vibrations in the same interval of time. The difference of one of these numbers from another and the relation of any one to another constitutes the fundamental ground for the distinction and relation between different tones in their degrees of pitch as high or low. Doubtless when we listen to notes thus related our perception carries little resemblance to one of numerical relations. It is not necessary for us to know anything of numbers and arithmetical proportions; and indeed when we do actually perceive a string vibrating, such vibration passes away without our being able to apprehend the numerical relation, while of course it is equally unnecessary for us to glance at the body in vibration at all, in order to receive the impression of its tone. An association, therefore, between the tone and its numerical relations may very possibly at first sight strike us, not merely as incredible, but we may receive the impression that its acceptance implies that our sense of hearing and ideal apprehension of harmonies suffer even depreciation when we look for their cause in that which is purely quantitative. However this may be, it is an undoubted fact that the numerical relation of vibrations in identical periods of time is the foundation of the specific definition of tones. The fact that our sense of hearing is essentially simple is no valid objection. The apparently simple impression, no less than the complex may, in respect to its essential character and existence, carry within its compass other aspects essentially multifold and related fundamentally to something different. When we perceive, for example, blue or yellow, green or red, in the specific purity of these colours, we receive in like manner the appearance of a perfectly simple determinacy, whereas violet readily is decomposed into its constituent colours of blue and red. Despite this fact the pure blue is not a simple fact, but a distinct correlation and fusion of light and shadow[446]. Religious emotions, a sense of right in any particular case, appear to us in the same way as simple; nevertheless all religious feeling, every impression that partakes of this sense of right, is related to ourselves in entirely different ways, though producing this simple feeling as its point of unity.