When my first child was about six weeks old, I attended a conference and heard about the Catechesis of the Good Shepherd. Everyone at the conference was invited to register for CGS training. I wanted to do so, but I knew that the timing was not right. Thus, I turned to the library and discovered a little gem by Sofia Cavaletti and Gianna Gobbi, Teaching Doctrine and Liturgy: The Montessori Approach. This book, printed in 1964 with photos and pictures, shows how Sofia Cavaletti drew from Maria Montessori in starting what would eventually become the Catechesis of the Good Shepherd.
I believe that the last paragraph in the book shares the key to the "Montessori method", the Catechesis of the Good Shepherd, and all successful education.
"The Montessori method is based on love, and the genius of the great educator lies in the fact that she made love the foundation for man's dealing with himself, his fellow men and with God."