History leads to philosophy when it raises in a fundamental way the question of truth. As we have seen, the term "truth," when applied to history, has a double meaning. It may mean that the record of what has happened is correct, and it may mean that the understanding of what has happened is correct. If the record is correct, its truth seems to be something fixed once for all and unchanging. The perfect record may never be possessed, but it seems to be ideally possible, because the events which the record would keep in memory must have happened, and, therefore, might have been recorded if fortune had been favorable. If, however, the understanding of what has happened is correct, its truth can not be something fixed once for all. It is fixed only from time to time. One correct understanding of what has happened does not displace another as truth might displace error, but one supplements and enlarges another. Histories which have gone before are not undone by those that follow after. They are incorporated into them in a very real way. Historical truth, therefore, when it does not mean simply the correctness of the records of history, is progressive. If the record of what has happened is correct, its truth is perpetual; if the understanding of what has happened is correct, its truth is contemporaneous. Now what does this distinction involve? Does it involve merely the recognition that facts may remain unchanged while our knowledge of them grows? A suspicion, at least, has been created that it involves something more, namely, the recognition that the facts themselves, being something "evolved and acted," are also progressive. Historical facts are careers in time. It is their occurrence which is recorded and it is their career which is understood. We may, therefore, undertake an inquiry into the nature of facts like these.