Pretty much what Corey said. Our subconscious holds all of our memories and feelings and stuff from the past even if we don’t recall it in our waking lives. Hence repressed memories and dejavu dreams or moments.
Memories, past events, reincarnation if you believe in that. That’s why old things come up in your dreams that you may not know where the heck they came from. They are memories that are stored in the subconscious that we may not consciously remember.
How to be Mr. Roboto!