During the various planes of development humans have a predisposition to acquire specific skills and knowledge.
“These periods correspond to special sensibilities to be found I creatures in the process of development; they are transitory and confined to the acquisition of a determined characteristic.” The Secret of Childhood p.34
“This guidance is exercised by making the child sensitive only towards certain things, leaving him indifferent towards others.” The Secret of Childhood p.37
“The child makes a number of acquisitions during the sensitive periods, which place him in relation to the outer world in an exceptionally intense manner. Then all is easy; all is eagerness and life, every effort is an increase of power.” –The Secret of Childhood, p. 36.