But I think it is better to stimulate the ambition required for overcoming difficulties, which can be done by grading the difficulties so that the pleasure of success may at first be won fairly easily. This gives experience of the rewards of persistence, and gradually the amount of persistence required can be increased. Exactly similar remarks apply to the belief that knowledge is difficult but not impossible, which is best generated by inducing the pupil to solve a series of carefully graded problems.
Source: On Education, especially in early childhood, 1926, Pt. 2：Education of character, chap. 14: General principles
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