How does it happen that children learn their mother tongue so well When we compare them with adults learning a foreign language, we often find this interesting fact. A little child without knowledge or experience often succeeds in a complete mastery of the language. A grown-up person with fully developed mental powers, in most cases, may end up with a faulty and inexact command. What accounts for this difference Despite other explanations, the real answer in my opinion lies partly in the child himself, partly in the behavior of the people around him. In the first place, the time of learning the mother tongue is the most favorable of all, namely, the first years of life. A child hears it spoken from morning till night and, what is more important, always in its genuine form, with the right pronunciation, right intonation, right use of words and right structure. He drinks in all the words and expressions which come to him in a flesh, ever—bubbling spring. There is no resistance: there is perfect assimilation. "Accounts for" in the last sentence of the first paragraph can be best replaced with