Bestselling Harvard psychology professor Pinker (The Blank Slate) investigates what the words we use tell us about the way we think. Language, he concludes, reflects our brain structure, which itself is innate. Similarly, the way we talk about things is rooted in, but not identical to, physical reality: human beings take “the analogue flow of sensation the world presents to them” and “package their experience into objects and events.” Examining how we do this, the author summarizes and rejects such linguistic theories as ”extreme nativism” and ”radical pragmatism” as he tosses around terms like “content-locative” and “semantic reconstrual” that may seem daunting to general readers. But Pinker, a masterful popularizer, illuminates this specialized material with homely illustrations. The difference between drinking from a glass of beer and drinking a glass of beer, for example, shows that “the mind has the power to frame a single situation in very different ways.” Separate chapters explore concepts of causality, naming, swearing and politeness as the tools with which we organize the flow of raw information. Metaphor in particular, he asserts, helps us “entertain new ideas and new ways of managing our affairs.” His vivid prose and down-to-earth attitude will once again attract an enthusiastic audience outside academia. (Sept.)