Maria Montessori wrote from a heart that was filled with lightning. Montessori's genuinely erudite exploration of attention, will, and imagination makes this book a profound treasure. Her analysis of spontaneous activity is essential reading -- for parents and teachers. And Montessori's exploration of the dangers of passive "learning" is fundamental to understanding that a person cannot escape the abyss of despair & meaninglessness if the will is trained to be passive -- a receiver of information or knowledge rather than a creator.
A note on the edition: It was difficult for me to find a good edition of this book. All the editions I found were reprints with at least a handful of glaring errors -- e.g., no page numbers. Still the power, vitality, vision, strength, and beauty of Montessori's arguments come shining through.