When Frederick Merk's Manifest Destiny and Mission in American History was published in 1963, some critics felt that this otherwise brilliant work was typical of one of the major weaknesses of contemporary historians: while historians have refined to precision the techniques of assembling and ordering information, they have paid little attention to the techniques of arriving at accurate and precise generalizations. The critics will undoubtedly be pleased with Professor Merk's new work, The Monroe Doctrine and American Expansionism, which is an outgrowth of the earlier book. His generalizations are accurate; his evidence, convincing. ""This book,"" he writes, ""is a study in the psychology of expansionism. It examines the combination of fears, suspicions, desires, and rationalizations by which the greatest expansionist drive in American history--that of the 1840's--was powered."" The author achieves his aims by employing a mode of presentation which is both informative and entertaining: he lets the period tell its own story. By citing newspaper editorials of the day, he maintains an effective dialogue between contending parties and between sections in the United States. Mr. Merk, emeritus professor of American history at Harvard, has produced a work of fundamental importance. Urbane in tone, refined in method, strict in criticism, The Monroe Doctrine and American Expansionism is one of those undertakings that does credit to American historical scholarship. Rich in basic information, incisive thought, and stimulating conclusions, this volume reads as well as it informs. A meticulously researched study which lends itself to line-by-line perusal, occasional browsing, and general reference, it merits attention from libraries.