Often a person would rather be with his opposite than with one who is nearer his own level. When two who are nearly of equal strength meet, they do not readily harmonize. Students of breath will easily understand this. They know that there is a more active breath and a less active breath, and that when they both become equally active there is a clash. If one person is a great singer and another is teaching voice-production they can agree together; there is no competition between them. The one wants to be heard, the other does not. But if two great opera-singers come together they will rarely agree; there will be a rivalry between them.