The Information Revolution is making preservation of digital records an urgent issue. Archivists have grappled with the question of how to achieve this for about 15 years. We focus on limitations to preservation, identifying precisely what can be preserved and what cannot. Our answer comes from the philosophical theory of knowledge, especially its discussion about the limits of what can be communicated. Philosophers have taught that answers to critical questions have been obscured by "failure to understand the logic of our language". We can clarify difficulties by paying extremely close attention to the meaning of words such as 'knowledge', 'information', 'the original', and 'dynamic'. What is valuable in transmitted and stored messages, and what should be preserved, is an abstraction, the pattern inherent in each transmitted and stored digital record. This answer has, in fact, been lurking just below the surface of archival literature. To make progress, archivists must collaborate with software engineers. Understanding perspectives across disciplinary boundaries will be needed.