Only recently, the entire field of theoretical knowledge and practical scientific work, which we conveniently call by the name of "defectology," was viewed as a minor part of pedagogy, not unlike how medicine views minor surgery. All the problems in this field have been posed and resolved as quantitative problems. Entirely accurately, M. Kruenegel states that the prevailing psychological methods for studying an abnormal child (A. Binet's metric scale or G. I. Rossolimo's profile) are based on a purely quantitative conception of childhood development as impeded by a defect (M. Kruenegel, 1926). These methods determine the degree to which the intellect is lowered, without characterizing either the defect itself or the inner structure of the personality created by it. According to O. Lipmann, these methods may be called measurement, but not an examination of ability, Intelligenzmessungen but not Intelligenzpruefungen (O. Lipmann, H. Bogen, 1923), since they establish the degree, but neither the kind nor the character of ability (O. Lipmann, 1924).