The foundational concept of Montessori's overall theory is that the young child has an absorbent mind. Thus, the child has a type of mind that absorbs knowledge, and therefore instructs himself. The child's mind is, from birth, forming itself and its organs (drawing an analogy to embryology) by its own natural impetus and direction. Environment is the key. The child who is making use of all that he finds around him, shapes himself for the future. Up until age 3, the child's mind is unapproachable by the adult, who can exercise no influence on it. From 3 to 6, the child is able to tirelessly concentrate upon an environment carefully crafted with his or her psyche in mind, absorbing its lessons.

Another fundamental concept in the theory is that of the "normal" child, the "true" child is revealed only when the environment is right. Defects of character which may have been present before age 3 are resolved during the ages of 3 to 6, if the provided environment plays to the power and nature of the absorbent mind.

The title of the book reflects the author's belief that the world which "has been torn to pieces" (presumably these words were written during or soon after WW2) can only be fundamentally reconstructed through education. Children create themselves, they create adults, and thereby they are the creators of culture and civilization and the whole world -- they are all-powerful in this sense, and therein lies the fundament of education as a cause of history.

Montessori also presents a notion of cosmic harmony, such that every organism is performing the role it was perfectly designed, through evolution, to perform. There is both a sense of a normally pleasant universe here, as well as a questionable assumption of some important extra-personal purpose for each of us. Not much in Montessori's program for 3- to 6-year-olds relies on this latter point, that I can find.

The book is recommended to be the first book by Maria Montessori for the parent of a teacher to read.