Researchers find evidence that neural systems actively remove memories, which suggests that forgetting may be the default mode of the brain. “Without forgetting, we would have no memory at all,” The reason, he thinks, is that the brain doesn’t know straight away what is important and what isn’t, so it tries to remember as much as possible at first, but gradually forgets most things. “Forgetting serves as a filter,” Hardt said. “It filters out the stuff that the brain deems unimportant.”