Humans are good at memory, as compared to goldfish, which are rumored to only have a recall of six seconds. Humans have also learned how to store memory in books, computers, films and more.
This matrix is a good way to think about memory.
Active remembering occurs when we take an ancient object, and study it to make meaning of our lives today. The holy scripts were written long ago, but they are actively remembered today all over the world, making the past as present.
Active forgetting takes place when people destroy knowledge deliberately. Heretical books were burnt along with their authors to eradicate their ideas.
Passive remembering can be imagined by visiting a museum. A pot stands there, but it doesn’t impact our lives today – it is past as past.
Passive forgetting took place right through history. Odd bits were dropped, buried and forgotten. There was no motive to keeping them. When discovered however, they can change our view of history by presenting information that we didn’t know before. For example, a shard of pottery might have the price of corn on it. If it is the same date as a holy script is purportedly meant to be, but they have different prices of corn, then guess what? – the holy text might be written later than clerics want it to be. It may not have been written by the author supposed to have written it. When objects that were passively forgotten are found, they can cause consternation in religious circles.