All questions as to methods of practising can be decided on well-known scientific principles which harmonize with experience, and need not be left in that loose and unsatisfactory condition when the dictum of some individual is substituted for principles capable of actual experimental demonstration. CHAPTER XIII. CHIEFLY AN APPLICATION TO VOICE PRODUCTION OF FACTS AND PRINCIPLES PREVIOUSLY CONSIDERED. Certain sounds may be made without the use of words or syllables, even without the employment of vowels or consonants, but intonation proper cannot be carried out without vowels, at least. The exact nature of vowels and consonants will be considered in the next chapter, but in the meantime it may be pointed out that a vowel is a free and open sound requiring for its production a certain form of the resonance-chambers. Neither vowels nor consonants are absolutely pure--that is, entirely free from foreign elements, from noise; but for all practical purposes a vowel is a pure sound, a consonant a sound accompanied inevitably by much noise. This noise is largely due to the difficulties of sounding consonants, the breath breaking against the vocal organs, especially the teeth, lips, etc., much as the waves of the sea against a rocky beach. So far then as musical quality is concerned, a consonant is an unmitigated nuisance. On the other hand, none but the most elemental communication by sounds could be carried out by the use of vowels alone. The consonants stop the breath-current, separate the vowels, and thus lay the foundation for the expression of ideas. Ideas imply differences; a new idea is conveyed by a new word, which in its simplest form is a syllable. When a consonant is introduced after a vowel sound, a momentary arrest is produced in the breath-flow, and this has its corresponding effect on the mind. It is, in fact, equivalent to a pause--say a comma or a period. If introduced before a vowel, it is marked off in a more definite way. The effect of this is to enable the ear the better to grasp the sounds. There is the principle of differentiation and the principle of rest, both highly important in all sensory and other psychic or mental processes. Consider the sentence "He is a man"--composed purely of monosyllables. Remove the consonants, and we have the following: "e i a a." Their ineffectiveness in conveying ideas is at once plain, for though "a man" conveys two ideas, such are not expressed by the vowels, which are identical, while "e" and "i" are common to too many words of one syllable to serve any useful purpose, alone, in the conveyance of _definite_ ideas. The consonants at once mark off the limitations; they fence around the ideas, so to speak. For the communication of ideas they are indispensable; nevertheless, being largely noises, they are musically abominable.