From ten or twelve years old until puberty a boy is apt to be very destitute of affection, and there is nothing to be gained by trying to force his nature. Throughout youth there is less occasion for sympathy than in adult life, both because there is less power of giving effective expression to it, and because a young person has to think of his or her own training for life, largely to the exclusion of other people’s interests.
Source: On Education, especially in early childhood, 1926, Pt. 2： Education of character, chap. 11: Affection and Sympathy
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