An interactive tool for organizing knowledge. It helps the user to record, change and search knowledge, and providesextensive error checking to ensure the internal consistency of the knowledge. Interaction with Knowledge Explorer uses simple English-like statements, commands and questions, plus UNIX-like conditionals, loops and methods. A smart menu interface prompts the user for all necessary information, and automatically generates the correct input syntax. Knowledge Explorer defines knowledge as an identification of the facts of reality, using words and sentences. The internal knowledge structure consists of entity-relation hierarchies with space-time-dependent events. The principal external knowledge structures are hierarchy outlines, relational databases and transliterated English.