Meaning of “You can turn over a new leaf every…”

Jo's Boys; the reassurance follows a setback and reframes a difficult year as experience that may later prove unusually helpful rather than simply wasted time.

The Majesty of Calmness, “Failure as a Success.” The passage is motivational interpretation, not a promise that every loss will produce a better outcome.

If—, third stanza; the surrounding passage describes losing one’s winnings and beginning again.

Self-Control, Its Kingship and Majesty, Chapter XIV, “Failure as a Success,” Project Gutenberg #51469. “Failure is often the turning-point...” follows Jordan’s account of a failed log-rafting experiment that nevertheless generated useful hydrographic observations. The word “often” is retained: this is conduct-of-life rhetoric about possible redirection after failure, not a guarantee that failure produces improvement.

As You Like It, Act II, Scene 1, Duke Senior; 1919 Yale Shakespeare edition edited by Jack R. Crawford, printed page 24 / Wikisource scan leaf 36. “Sweet are the uses of adversity” occurs in Duke Senior’s Forest of Arden reflection on exile, winter and the lessons he claims to find outside court life. It remains fictional dramatic speech rather than Shakespeare’s autobiographical advice or a modern psychological claim about hardship.

Final line of Ode to the West Wind; the changing seasons become a metaphor for historical and personal renewal.