Darwin notes that even a perfect musical scale can be found in nature. He says[]:
It is a remarkable fact that an ape, a species of the gibbon family, produces an exact octave of musical sounds, ascending and descending the scale by half tones. From this fact, and from the analogy of other animals, I have been led to infer that the progenitors of man probably uttered musical tones, and that consequently, when the voice is used under any strong emotion, it tends to assume, through the principle of association, a musical character.
It has been further demonstrated that the strength of the sensory impressions from certain sounds is due to the structure of the ear, and that generally a particular kind of sound produces a similar kind of emotional effect in animals as in man. Obviously the musician is powerless to do more than widen or deepen this effect. Colvin admits that the musician sometimes directly imitates, as when he produces the notes of birds or the sounds of natural forces, or when he represents particular emotions; but he regards the former instances as hazardous and exceptional, and indicates that a particular emotional harmony may affect the hearers differently. True, but the hazard of the first condition is the result of the limitations of the artist, and the second condition is the consequence of the limitations of the art. The effect of music being purely sensorial must vary with the emotional conditions surrounding the hearer. The musician does what he can, but he is unable to go so far as the poet and produce an emotional effect which will with certainty be recognized by every person affected, at all times, as having the same particular bearing.
Taine separates music ("properly so called" as distinguished from dramatic music) and architecture from the imitative arts, as they "combine mathematical relationships so as to create works that do not correspond with real objects."[c] Obviously the whole purpose of dramatic music is to imitate the effects of the passions, but its necessary inclusion amongst the imitative arts upsets the dictum of Taine, for the emotional effects of one kind of music only differ from those of another kind when they differ at all, in the character of the natural emotional effects represented.
In the case of the architect, seeing that his art is subordinated to utility, his scheme, his measurements, and the character of his materials, are largely or almost entirely governed by conditions outside of his art, and consequently it is only possible for him to represent nature to a limited extent. Rarely can he vaguely suggest a natural aisle beneath the celestial dome, a rock-walled cave whose roof soars into obscurity, or a fairy grotto backed by a beetling cliff. Sometimes he may cause us to experience similar effects in kind to those we feel when we recognize grandeur in nature, but usually he is compelled to confine his beauty to harmonies produced by symmetrical designs of straight lines and curves. But in his simplest as in his most complex designs, he must follow nature as closely as possible. Purely ornamental forms always appear more beautiful when the parts have a direct mathematical relationship with each other than when they have not; that is to say, when the parts appear to be naturally related. Thus, that a cross appears to be less agreeable to the sight when the horizontal bar is below the centre of the perpendicular than when it is above this point, is due to what appears to be a want of balance because the form is unobservable in nature. In trees the horizontal parts are usually above the middle of the height of the observable trunk, and in the exceptions nature gives the whole tree a conical or other shape, the relative position of the horizontal parts being obscured in the general form.
As with parts of forms, so with the forms as wholes. Other things being equal, that design is the best where the forms are directly proportioned one with the other and with the whole, and this is because we are accustomed to the order of design in nature where everything is balanced by means of direct proportions and corresponding relations. The architect therefore, like the musician or poet, must represent nature so far as he can within the limits of his art, though his representation is comparatively weak owing to the artificial restrictions imposed upon him.
[a] Article on "Fine Arts," Encyclopædia Britannica, 11th Edition.
[] The Expression of the Emotions in Man and Animals.
[c] On the Ideal in Art.