The first expression of life is expansion. Almost every student in beginning the development of the voice is tempted to make too much effort. In nearly all cases this will be misplaced. He will especially tend to accentuate contraction, with little or no sympathetic expansion. Resolution and earnestness will normally cause expansion, for at first the contraction is simply an added expression of control. To begin with contraction violates nature's primary law.
The first effort accordingly must be to stimulate activity in the extensor muscles. The student must realize that any awakening of his imagination and feeling, and genuine quickening of his interest, must first cause sympathetic expansion, especially of his torso. It must also kindle his face and increase his pulsation of life through his whole body. Imagination and emotion, when natural, first affect the muscles concerned in the sympathetic and harmonious actively or expansion of the body.
The whole torso must be expanded. This gives room for free action of the lungs and diaphragm. It also establishes the primary condition for normal sympathetic vibration. Thought, imagination, and emotion attune the whole body as the sounding board of the voice, and this work is initiated by a harmonious expansion and a certain unity of all parts of the body.
—Curry, Samuel S. Mind and Voice: Principles and Methods of Voice Training (1910): 28. Student of Francesco Lamperti.