At the center of the extraordinary work that Ulric Neisser has so far accomplished is, I believe, a creative tension. On one hand, Neisser is a synthesizer and a unifier, who aims to forge an integrated art and science of cognition. Cognition, as Neisser studies it, cannot be a collection of isolated facts and curiosities; it must be an interconnected system of general principles and common themes. These themes should allow one to see connections between processes as diverse as reaching for objects, identifying faces or words, charting courses through the layout, reminiscing about one’s childhood, dreaming, imagining, and arriving at solutions to problems. Neisser’s first great step toward this unificationdistilled in his book Cognitive Psychology (1967)—inaugurated a field. His second step-Cognition and Reality (1976), a work at the center of my own intellectual foundations-is an agenda-setting effort to orient the study of human knowledge toward the meaningful problems that perceivers, thinkers, and actors encounter.