you can't put an old head on young shoulders

Noun

 * 1) Young people inevitably lack the experience and wisdom which come with age.
 * 2) * 1901, Pauline E. Hopkins, Hagar's Daughter, ch. 25 (Google preview) (in The Magazine Novels of Pauline Hopkins, Oxford, 1990, ISBN 9780195063257:
 * "Young men will be young men; you can't put an old head on young shoulders," he added, repeating trite sayings as if they were original with himself.
 * "Young men will be young men; you can't put an old head on young shoulders," he added, repeating trite sayings as if they were original with himself.