Voice is the vibration of the air, and is like the waves of the sea. The voice is produced through the instrumentality of the lips, throat, teeth, tongue, etc. These cause a wave in the air, and this wave reaches the nerve of the ear, which is thereby affected. This is the voice.
There are two kinds of voices. One when the complete instrument is perfect, then the emission of sound is perfect. The second is when the instrument is imperfect, it affects the voice in such a way that it is far from pleasing. What we have just said refers to the voice itself.
It is natural for the heart and spirit to take pleasure and enjoyment in all things that show forth symmetry, harmony, and perfection. For instance: a beautiful house, a well designed garden, a symmetrical line, a graceful motion, a well written book, pleasing garments -- in fact, all things that have in themselves grace or beauty are pleasing to the heart and spirit -- therefore, it is most certain that a true voice causes deep pleasure.
What is music? It is a combination of harmonious sounds. What is poetry? It is a symmetrical collection of words. Therefore, they are pleasing through harmony and rhythm. Poetry is much more effective and complete than prose. It stirs more deeply, for it is of a finer composition.
A fine voice when joined to beautiful music causes a great effect, for both are desirable and pleasing. All these have in themselves an organization, and are constructed on natural law. Therefore, they correspond to the order of existence like something which would fit into a mold. A true voice fits into the mold of nature. When it is so, this affects the nerves, and they affect the heart and spirit.
In the world of existence physical things have a connection with spiritual realities. One of these things is the voice, which connects itself with the spirit; and the spirit can be uplifted by this means -- for though it is a physical thing, it is one of the material, natural organizations -- therefore, it is effective.
All forms when understood aright gladden the spirit. Melodies are like water. The voice is like a goblet. The pure water in a pure glass is pleasing. Therefore, it is acceptable. But even though the water be pure, if it be in a goblet which is not so, this receptacle will make it unacceptable. Therefore, a faulty voice even though the music be good, is unpleasing.
In short: melodies, though they are material, are connected with the spiritual, therefore, they produce a great effect. A certain kind of melody makes the spirit happy, another kind makes it sad, another excites it to action.
All these feelings can be caused by voice and music, for through the nerves it moves and stirs the spirit. Even over animals, music has an effect. For example: When they wish to take a camel over a desert road, they attach to him some bells, or they play upon a flute, and this sound prevents him from realizing the fatigue of the journey; his nerves are affected, but he does not have an increase of thought, he feels nothing but physical sensation.
Whatever is in the heart of man, melody moves and awakens. If a heart full of good feelings and a pure voice are joined together, a great effect is produced. For instance: if there be love in the heart, through melody, it will increase until its intensity can scarcely be borne; but if bad thoughts are in the heart, such as hatred, it will increase and multiply. For instance: the music used in war awakens the desire for bloodshed. The meaning is that melody causes whatever feeling is in the heart to increase.
Some feelings occur accidentally and some have a foundation. For example: some people are naturally kind, but they may be accidentally upset by a wave of anger. But if they hear music, the true nature will reassert itself. Music really awakens the real, natural nature, the individual essence.
With whatever purpose you listen to music, that purpose will be increased. For instance: there will be a concert given for the poor and unfortunate, and if you go there thinking of the aim, the music will increase your compassion and generosity. This is the reason why music is used in war. And so it is with all the things that cause the excitation of the nerves. ('Abdu'l-Bahá's words to Mrs. Mary L. Lucas, as quoted in "A Brief Account of My Visit to Acca", Chicago: Bahá'í Publishing Society, 1905, pp. 11-14; The Compilation of Compilations vol II, pp. 77-79)
