A lesson can arrive as a detail that refuses to fit your explanation.

Understanding tends to improve by irritation rather than revelation. You have an account of something that works well, and then one detail will not sit in it, and the immediate temptation is to call that detail an exception and move on. The awkward fact is usually the most valuable thing you have. It is the only part of the situation not already agreeing with you.

Keep a note of what will not fit instead of dismissing it, and return to it in a fortnight. Ask what would have to be true for it to be ordinary rather than exceptional. That question is where most changes of mind begin.