I’ll turn over a new leaf.

The phrase “I’ll turn over a new leaf” is an idiom meaning to reform one’s behavior, begin again with better intentions, or make a fresh start after past mistakes. Its imagery comes from turning a page (“leaf”) in a book—leaving the old page behind and beginning anew. Although often attributed to famous writers, this expression circulates widely in English as a set phrase and is frequently detached from any single, verifiable literary moment. In a quotations database, it is best treated as a proverb/idiom unless a specific, citable Cervantes passage in a particular translation can be identified.