The formative period (birth to seven) is seen as the period of greatest physical growth and development. Structures in the brain are being refined and elaborated, and young children's primary mode of learning is through doing and experiencing - they "think" with their entire physical being.
The nature of this early learning should be self-motivated, allowing children to come to know the world in the way most appropriate for their age - through active feeling, touching, exploring and imitating; in other words, through doing. Only when new capabilities appear, around the seventh year, is the child physically, emotionally and intellectually ready for formal instruction.
The Tasks and Content of the Steiner Waldorf Curriculum edited by Kevin Avison and Martin Rawson