There's a box of old letters in most attics and it doesn't get opened often. When it does, the surprise is how much had been forgotten and how differently it reads now.
Calling the past a lesson isn't the same as calling it fair. Some of it shouldn't have happened at all. The learning came out of what you did afterwards, which was yours.
The useful question isn't what it meant. It's what it taught you to notice, and whether you're still applying a rule that stopped being true some time ago.