"The Sensory Order," first published in 1952, sets forth F. A. Hayek's classic theory of mind in which he describes the mental mechanism that classifies perceptions that cannot be accounted for by physical laws. In it, Hayek independently developed a "Hebbian learning" model of learning and memory – an idea which he first conceived in 1920, prior to his study of economics. Hayek's expansion of the "Hebbian synapse" construction into a global brain theory has received continued attention in neuroscience, cognitive science, computer science, behavioural science, and evolutionary psychology. Hayek posited two orders, the sensory order that we experience, and the natural order that natural science has revealed. Hayek thought that the sensory order is in fact a product of the brain. He characterized the brain as a highly complex but self-ordering, hierarchical classification system, a huge network of connections. "A most encouraging example of a sustained attempt to bring together information, inference, and hypothesis in the several fields of biology, psychology, and philosophy."-Quarterly Review of Biology