When the sensitive period has disappeared, intellectual victories are reported through reasoning processes, voluntary efforts, and the toil of research. And from the torpor of indifference is born the weariness of labour.

Maria Montessori, The Secret of Childhood

Cosmic education seeks to offer the young, at the appropriate sensitive period, the stimulation and help their need to develop their minds, their vision and their creative power, whatever the level or range of the personal contributions may be.

Mario Montessori Jr, Education for Human Development

There is no going back. What a child's mind assimilates during the sensitive period remains as a permanent acquisition for his whole life, and it can never be acquired at another stage.

Maria Montessori, The Discovery of the Child

Nature's method is to give the child special interests of exceptional intensity for doing the special creative work, necessary for each part of his developing personality.

Maria Montessori, The Absorbent Mind