In school, we first learn the lessons and then take the test. In life, it's the opposite – first comes the test, and then we learn the lesson. Source: Internet
That men do not learn very much from the lessons of history is the most important of all the lessons of history. Aldous Huxley
Mistakes are a part of being human. Appreciate your mistakes for what they are: precious life lessons that can only be learned the hard way. Unless it's a fatal mistake, which, at least, others can learn from. Al Franken
There are no mistakes, only lessons. Chinese Proverb
time, as he grows old, teaches many lessons. Romanian Proverb