I Forgot Who Told Me About Forgetting

As I was battling my way through my younger days, I can remember being told by several of my elders that they "have forgotten more than you will ever know." Now that I have been granted the right to be an elderly person myself, I can't remember who it was that told me that stuff and I really don't remember anybody explaining what they meant by it. I certainly see no reason to brag about it.