Animals of the same species vary in their musical gift, as they do in other points. Some animals are very fond of music and greatly affected by it, while others are insensible or quite averse to it; of the former the horse has already in remote antiquity been mentioned for its joy at the sound of the trumpet, as we read in the book of Job (xxxix, 25). Shakespeare also says in his "Merchant of Venice":
Or race of youthful and unhandled colts,
Fetching mad bounds, bellowing, and neighing loud,
Which is the hot condition of their blood;
If they but hear perchance a trumpet sound,
Or any air of music touch their ears.
You shall perceive them make a mutual stand,
Their savage eyes turned to a modest gaze,
A touching proof of this old truth was given in the late Franco-German War, when, in the evening after the battle of Gravelotte, on the trumpet-signal for the roll-call of the Life-Guards, more than three hundred riderless horses, some of them wounded and hobbling on three legs, answered the well-known sounds and mustered with the remnant of their regiment.
Of the nightingale it is said that in spring the males perch on a tree opposite the hens and sing their best one after another; where-upon the hens select their mates and fly off with them.
The intervals we observe most in the voices of animals are fifths, octaves, and thirds, and also fourths and sixths.
In inanimate sounding bodies, as in church-bells, in the larger strings of the piano, in the Æolian harp (or wind-harp), the fifth and tenth (or third in the next higher octave), commonly called harmonics, are very distinctly heard toward the end of the principal sound.
The human voice in speaking uses also these intervals foremost, but it moves also over most of the other intervals in melodious and harmonious combinations. We speak in melodies and harmonies, improvising them by the impulse of our thoughts and feelings over an extent or compass of one and a half to two octaves; as every plant grows with a certain color, so every sentence is spoken in some melody which rises in sympathy with the sense and sentiment of the words, giving character to the whole sentence; and from the quality and accent of this musical investment, the truth and sincerity of the words may be felt, and the character of the speaker be traced.
Sentences are spoken in a certain musical key, and are mostly begun on the fifth or dominant of the scale of the key-note, from which they descend in seconds or thirds or other intervals to the key-note, and, may be, down to the lower dominant:
