A yet further trait of strong feeling, similarly accounted for, was the employment of larger intervals than are employed in common converse.  This trait, also, every ballad and aria carries to an extent beyond that heard in the spontaneous utterances of emotion:  add to which, that the direction of these intervals, which, as diverging from or converging towards the medium tones, we found to be physiologically expressive of increasing or decreasing emotion, may be observed to have in music like meanings.  Once more, it was pointed out that not only extreme but also rapid variations of pitch are characteristic of mental excitement; and once more we see in the quick changes of every melody, that song carries the characteristic as far, if not farther.  Thus, in respect alike of loudness, timbre, pitch, intervals, and rate of variation, song employs and exaggerates the natural language of the emotions;—­it arises from a systematic combination of those vocal peculiarities which are the physiological effects of acute pleasure and pain.

Besides these chief characteristics of song as distinguished from common speech, there are sundry minor ones similarly explicable as due to the relation between mental and muscular excitement; and before proceeding further these should be briefly noticed.  Thus, certain passions, and perhaps all passions when pushed to an extreme, produce (probably through their influence over the action of the heart) an effect the reverse of that which has been described:  they cause a physical prostration, one symptom of which is a general relaxation of the muscles, and a consequent trembling.  We have the trembling of anger, of fear, of hope, of joy; and the vocal muscles being implicated with the rest, the voice too becomes tremulous.  Now, in singing, this tremulousness of voice is very effectively used by some vocalists in highly pathetic passages; sometimes, indeed, because of its effectiveness, too much used by them—­as by Tamberlik, for instance.

Again, there is a mode of musical execution known as the staccato, appropriate to energetic passages—­to passages expressive of exhilaration, of resolution, of confidence.  The action of the vocal muscles which produces this staccato style is analogous to the muscular action which produces the sharp decisive, energetic movements of body indicating these states of mind; and therefore it is that the staccato style has the meaning we ascribe to it.  Conversely, slurred intervals are expressive of gentler and less active feelings; and are so because they imply the smaller muscular vivacity due to a lower mental energy.  The difference of effect resulting from difference of time in music is also attributable to the same law.  Already it has been pointed out that the more frequent changes of pitch which ordinarily result from passion are imitated and developed in song; and here we have to add, that the various rates