This short book, based on four lectures given at Barcelona in 1926, is a survey of the important psychologic problems in the study of intelligence and the measurement of mental development. It is a very concise presentation, but is none the less comprehensive. The author tries to relate the theoretical aspects of the problem and the increasing body of fact gained from practical experience with psychologic tools.
The first lecture deals with the stages of mental development of the individual as a unified organism and as a part of the social group. The second lecture on the measurement of developmental levels gives a critical discussion of various mental tests, of the rate of mental growth and of the limit of growth. In the third and fourth lectures this discussion is carried further, and the importance of an analytic study of the individual's mental development is emphasized. The author points out