Memories.
Memories can be a boon or a curse. It would be nice to write injuries and harsh words in the dust. Then we would write all pleasant happenings in marble. The dust would blow away but the marble would endure.
Impossible? No! We can do even better by using our memories correctly. Memory tends to recall only people or events that make a deep impression. Feelings, our reactions to people and events, are the etching tools that make memories strike deep root.
If you want to forget the unpleasant and recall the happy events, control the etching tool. Don't brood over the unpleasant. Anger, revenge, discouragement, hatred and jealousy groove the event into your memory. You can be sure it will be back to haunt you. Control the adverse feelings. Concentrate on pleasant events. Etch them with feelings of courage, responsibility, sincerity, and love. Then your memories will be a blessing.