This phrase means that in life, you sometimes fail or make mistakes, but in the end, if you stay focused and keep trying, you will eventually be successful. The comparison to “mischief†means that even if you sometimes make mistakes or do something wrong, it may seem like you can’t win. But if you keep trying and don’t give up, you will eventually be successful. Mischief is the wayward and seemingly unstoppable force, which will eventually outlast and prevail over more careful, but more fleeting accomplishments. So even if you have a temporary setback, you can still come out on top in the end if you stay focused and don’t give up.