Certain vowels and consonants are usually held to be especially favored by a "forward position," and exercises on these are very widely used for securing a "forward" tone. These exercises are described in a later paragraph. It will be noticed however that this use of vowels is not an application of the theory of "forward emission." The vowel sounds are believed to owe their "forward position" to resonance, while "emission" is purely a matter of direction or focusing of the breath-blast. The whole subject of emission and forward placing is in a very unsatisfactory condition. _The Traditional Precepts in Modern Instruction_ So much importance is attached by modern teachers to the traditional precepts of the old school that this subject calls for somewhat lengthy treatment. Before discussing the manner in which the precepts are applied in practical instruction, it will be well to review first the interpretations of the precepts offered by different vocal scientists. It must be remarked, in the first place, that no single one of the precepts has ever been satisfactorily explained; that is, no direct means of performing the actions indicated by the precepts has ever been found. If ever the precepts had a definite meaning, considered as specific directions for performing certain actions in a special way, that meaning has been lost. Mechanical analysis has not reduced the precepts to a form in which they are of direct value to the modern teacher. That the "forward tone" is interpreted as a reference to the emission of the voice was noted earlier in this chapter. The explanation of the "open throat" precept as a function of mouth-pharynx resonance has also been mentioned. "Singing on the breath" is a very perplexing subject for vocal theorists. Many authorities assert that this precept describes an effect obtained by the "opposed muscular action" breath-control. (See citation from Shakespeare in Chapter II.) But this explanation is hardly satisfactory; if the precept had meant no more than breath-control, it would have been forgotten long ago. The "support of the tone" is mentioned by a large number of theoretical writers on the voice. These writers generally state, in substance, that "the tone must be supported by the breathing muscles of the chest, and not by the throat muscles." (See _The Technics of Bel Canto_, by G. B. Lamperti, New York, 1905.) But this explanation is hardly to be considered as a scientific doctrine. Every one knows that a tone has no weight, so in the physical sense it can need no support. In short, scientific analysis has thrown no more light on this than any other of the old precepts.