Modern methods of instruction in singing can be understood only by following out this idea of conflict between known facts and accepted, though erroneous, scientific doctrines. As we have seen, the only universally accepted theory of supposedly scientific Voice Culture is the idea of direct mechanical guidance of the voice. Every vocal teacher attempts to make his empirical knowledge conform to this mechanical idea. As the empirical knowledge is correct, and the mechanical idea a complete mistake, conflict between the two is inevitable. Every modern teacher of singing possesses in full measure the empirical understanding of the voice. To this statement hardly an exception need be made. Probably the most startling fact concerning the wide diffusion of this knowledge is that the nature of this knowledge is so thoroughly ignored. Because the psychological process is purely sub-conscious, empirical knowledge is always indirectly and generally unconsciously applied. In the teacher's mind the most prominent idea is that of mechanical vocal guidance. His attention is always directly turned to this idea. Empirical knowledge, consisting merely of a succession of auditory and muscular sensations, lurks in the background of consciousness. To the intelligent vocal teacher there is something peculiarly fascinating about the study of tone-production. In listening to any faulty singer we feel with the utmost precision what is wrong with the voice. Each imperfect tone informs us clearly and definitely just where the wrong muscular contraction is located. It seems so easy to tell the singer what to do in order to bring the tone out perfectly. Under the influence of the mechanical idea we try to express this feeling in the terms of muscular action. This attempt is never successful; the singer cannot be brought to understand our meaning. Yet it is so clear in our own minds that our inability to express it is extremely tantalizing. We go on, constantly hoping to find a way to define the mechanical processes so clearly indicated to the ear. We always feel that we are just on the verge of the great discovery. The solution of the problem of tone-production is almost within our grasp, yet it always eludes us.