Libraries have cataloged the world's published record for over a century, but that description sits as text inside records rather than as identifiable things. We have spent the past several years rebuilding it as a knowledge graph. WorldCat Entities publishes descriptions of people, events, places, organizations, and works as persistent, resolvable URIs. The Dewey Decimal Classification is published on the same basis, which turns a familiar classification scheme into a machine-navigable hierarchy of human knowledge.