Li briefly outlines three generations of intelligence research over the past 100 years with attention to the origins and limitations of early investigations and the resulting confusion and disagreement in modern reinterpretations of the findings. He discerns an emerging consensus among scholars and researchers that intelligence should be considered primarily as a product of thinking and learning. To find the essence of how thinking is possible and what learning is, Li investigates theory and research in cognitive psychology, developmental linguistics, animal behavior, and many other...