content since they are all we have; from them we infer what the event was, we affirm that it is a fact that the event was so and so. We do not say "Lincoln is assassinated"; we say "it is a fact that Lincoln was assassinated." The event was , but is no longer; it is only the affirmed fact about the event that is , that persists, and will persist until we discover that our affirmation is wrong or inadequate. Let us then admit that there are two histories: the actual series of events that once occurred; and the ideal series that we affirm and hold in memory. The first is absolute and unchanged -- it was what it was whatever we do or say about it; the second is relative, always changing in response to the increase or refinement of knowledge. The two series correspond more or less, it is our aim to make the correspondence as exact as possible; but the actual series of events exists for us only in terms of the ideal series which we affirm and hold in memory. This is why I am forced to identify history with knowledge of history. For all practical purposes history is, for us and for the time being, what we know it to be. It is history in this sense that I wish to reduce to its lowest terms. In order to do that I need a very simple definition. I once read that "History is the