I saw the following sentence at http://www.learnersdictionary.com/qa/-Come-Back-and-Get-Back- :
I had forgotten a lot of what I learned about music, but it's all coming back to me now.
The past perfect is supposed to describe events that happened prior to those described by the simple past, so I'm wondering whether the simple past "forgot" should be used in place of "had forgotten" and the past perfect "had learned" instead of "learned."
I'd appreciate your help.