The Big Book of Concepts - by G.L. Murphy

Concepts are the glue that holds our mental world together.Our concepts embody much of our knowledge of the world, telling us what things there are and what properties they have. It may not seem to be a great intellectual achievement to identify a bulldog or to know what to do with a tomato, but imagine what our lives would be like without such a conceptual ability. We might know the things we had experienced in the past—a particular chair, our bed, the breakfast we had today, our science teacher, etc.—but when we encountered new exemplars of these categories, we would be at a loss.