In the quotes from Yancey she is trying to get her point across by telling us that basically we learn from our mistakes one way or another. I believe that is why she states as they learn they witness their own learning because as we learn we learn about the things that do and do not work for us and when we sit back and take a minute to reflect we open up a new window of learning for ourself because if we take the time to reflect on it then we think harder about it.