This edifying collection of letters between two titans of American legal thought will be a welcome addition to the library of any student of legal theory, legal history, or the Supreme Court. Editors Mennel (History/Univ. of New Hampshire) and Compston (former director of the National History Education Network) have compiled and annotated the personal correspondence of two of America's preeminent legal minds, Oliver Wendell Holmes and Felix Frankfurter. When they first met and began corresponding, Holmes, though in his 70s, was at the height of his formidable powers--a sitting Supreme Court justice and the author of leading texts on American law. Frankfurter was a highly respected attorney and an ebullient and brilliant young professor at Harvard Law School. In Holmes, Frankfurter found a mentor and sponsor worthy of deification. ``For you to call my work `really A1,' '' Frankfurter wrote to Holmes, ``is to be knighted by the King!'' In Frankfurter, Holmes found a doting pupil whose exhilaration and youth rejuvenated the aging and cynical justice: ``Even your more optimistic outlook and prophecy for human destinies than I can venture upon makes you dearer to me.'' Spanning the period from 1912 through 1934, their never-before-published letters present in a terse microcosm not only the heart of American legal theory, but indeed the core of early-20th-century American intellectual development. They do not contain lengthy exegeses of jurisprudence but lively snippets of philosophy along with politics and gossip. The editors open the collection with a useful but, for the uninitiated, too brief introduction to the philosophies and history of Holmes and Frankfurter. They have, however, supplied rich annotations regarding the individuals, legal cases, books, and events alluded to by the two men. This, then, is a most useful addition to the existing biographies and commentaries regarding Holmes, Frankfurter, and their contemporaries.