( saying ) used when a small child has just said sth that seems very wise or clever
OUT OF THE MOUTHS OF BABES (AND SUCKLINGS)
Meaning of OUT OF THE MOUTHS OF BABES (AND SUCKLINGS) in English
Oxford Advanced Learner's English Dictionary. Оксфордский английский словарь для изучающик язык на продвинутом уровне. 2005