 What makes memorial seemings a source of justification? Is it a necessary truth that, if one has a memorial seeming that p, one has thereby prima facie justification for p? Or is memory a source of justification only if, as coherentists might say, one has reason to think that one’s memory is reliable? Or is memory a source of justification only if, as externalists would say, it is in fact reliable? Also, how can we respond to skepticism about knowledge of the past? Memorial seemings of the past do not guarantee that the past is what we take it to be. We think that we are older than five minutes, but it is logically possible that the world sprang into existence just five minutes ago, complete with our dispositions to have memorial seemings of a more distant past and items such as apparent fossils that suggest a past going back millions of years. Our seeming to remember that the world is older than a mere five minutes does not entail, therefore, that it really is. Why, then, should we think that memory is a source of knowledge about the  past?[57]