Diseases of school children treated, causes left undisturbed Discoveries of experimental psychology: overwork; nervous exhaustion Science is confronted by a mass of unsolved problems. Laws governing fatigue still unknown Toxines produced by fatigue and their antitoxins Joy in work the only preventative of fatigue Real experimental science, which shall liberate the child, not yet born CHAPTER III MY CONTRIBUTION TO EXPERIMENTAL SCIENCE The organization of the psychical life begins with the characteristic phenomenon of attention. Incident which led Dr. Montessori to define her method Psychical development is organized by the aid of external stimuli, which may be determined experimentally. Tendency to develop his latent powers exists in the child's nature Environment should contain the means of auto-education External stimuli may be determined in quality and quantity. Educative material used should contain in itself the _control of error_ Quantity of material determined by the advent of abstraction in pupil Relation of stimuli to the age of the pupil Material of development is necessary only as a starting point. Corresponds to the terra firma from which the aeroplane takes flight and to which it returns to rest Establishing of internal order, or "discipline" Psychical growth requires constantly new and more complex material Difference between materials of auto-education and the didactic material of the schools Psychical truths. "Discipline" the first external sign of a psychical reaction to the material Initial disorder in Montessori schools Psychical progress not systematic but "explosive in nature" Birth of individuality Intellectual crises are accompanied by emotion Older child beginning in system, chooses materials in inverse order Course of psychical phenomena explained by diagrams Tests of Binet and Simon arbitrary and superficial Problems of psychical measurement Observing the child's moral nature Transformation of a "violent" child and of a "spying" child in a Montessori school Polarization of the internal personality Guide to psychological observation. Work Conduct Obedience CHAPTER IV THE PREPARATION OF THE TEACHER The school is the laboratory of experimental psychology Qualities the new type of teacher must possess CHAPTER V ENVIRONMENT Physical hygiene in the school The requirements of psychical hygiene Free movement. Misconceptions of physical freedom Action without an aim fatigues Work of "preservation" rather than "production" suitable to children CHAPTER VI ATTENTION Awakens in answer to an impulse of "spiritual hunger" Attention cannot be artificially maintained by teacher _Liberty_ the experimental condition necessary for studying phenomena of attention Child's perception of an internal development makes the exercise pleasant and induces him to prolong it