"Non-fiction", on the other hand, declares itself to be the carrier of fact, an expression of reality, and thus of truth. Why then does most fact-based work have a remarkably short shelf life? The reply might be that additional facts come along. That we are learning all the time. In that case, it was never an expression of reality or truth. And even if the facts are overtaken, the arguments built upon them should not date with such terrifying rapidity. Decade-old serious "non-fiction" often seems arcane, irrelevant. The written style itself seems to become old-fashioned. Two-centuries-old decent "fiction" on the other hand can easily remain fresh.