Available for the first time in an English translation, the book reports the results of a series of studies undertaken in the early 1960s on the cognitive development of children with congenital blindness. Chapters one and two review the literaure on such topics as the concept of sensory compensation and the nature of tactual space and provide working hypotheses within a Piagetian framework on sensory deprivation and intelligence. The general hypothesis is that there is a genetic relationship between adequacy of materials on which operations are based and the development of these operations themselves. Part two presents the results of studies on the formation of the reasoning process in blind children. Conclusions are reported in terms of three major topics: (1) characteristics of functional development of the congenitally blind; (2) figurative structures, language and function; and (3) visual deprivation and learning--relations between object and subject. Translations of the original introduction and preface are supplemented by a new introduction for the English edition by the author and a new preface by the translator. An afterword discusses recent applications of the research; a glossary, bibliography, and index are provided. (CL)