A memory is forgotten when there’s no one to keep it alive. Suppose you have a memory of going to the beach when you were ten. You remember the hot sun hitting your skin, the sand beneath your toes, how you played in the water for two hours, how you collected a couple of dozen seashells, your whole family there with you, mom, dad, little brother, grandma, aunt, uncle, cousin. You remember watching the sunset the last night you were there and how it’s vibrant pink and orange colors lit the beach up. Not only that, but you remember trying a coconut for the first time and the sweet taste. You remember this week so vividly that you can almost relive it when thinking about it. You grow up and the memory fades or alters a little. You’re now thirty, and you only remember the whole family visiting the beach. You remember watching a sunset. You remember playing in the water a long time. You remember trying a coconut. You remember finding seashells. Then you get even older,, and now you’re sixty and have grandchildren to tell this story to. You tell them you went to the beach with your family, that’s where you tried a coconut, you still have a couple of seashells you collected, you remember you saw your favorite sunset then. Now you’re no longer here and your grandchildren have to save the memory. They tell their children about you, how you loved your trip to the beach and that they have one of the seashells you had collected. Next it’s your great-grandchildren who can tell the story. Somehow it’s brought up you always told a story about going to the beach, and somewhere they have seashells from that, probably in a box in their attic. Then years go on and the box with the last seashell gets donated to a thrift store. No one knows where that seashell came from or who owned it, how they found it or bought it. That seashell sits in a thrift shop and is bought by a crafter. They use it as a decoration, not knowing the forgotten memory behind it. Ok