英语俚语 turn over a new leaf

几天内竟然N多次听到了这个俚语, 看来不拿来讲讲都不行了.呵呵
先看answers里的解释:Make a fresh start, change one's conduct or attitude for the better, 中文解释为重头来过.
例句: He promised the teacher he would turn over a new leaf and behave himself in class.

对于这个俚语的来源, answers并没有提供详细的资料. 只是提到这个俚语自从1500年就存在了. 它其实是由 turn the page of a book to a new page而来的. 至于为什么把page换成了leaf, 还有待考证.