What would you think of an analysis of more than 400 datasets? John B. Carroll has given us an impressive review of the factorial analytic studies covered most of the human cognitive abilities. But, he has gone beyond the re-analysis level and has made up a new model of intelligence: "The three strata model" which will help us to avoid hopeless discussions about the nature of the most important cognitive abilities and to advance in the actually interested topics about such abilities. Specially, he finishes with the argument about the existence of the g factor but, he also recognizes the importance of the Thurstone's primary mental abilities and the Cattell and Horn's distinction between fluid and crystallized intelligence. I think everyone concerned in the cognitive abilities field should read this book and keep "The three strata model" in mind in the analysis of his/her research.