"The 2013 digitization of the vast Hartlib Papers archive highlighted the pressing need for a comprehensive modern study of Samuel Hartlib (1600-1662), a central figure in seventeenth-century intellectual life. Though educated in Eastern Europe, Hartlib spent his adult life in London, where he became a prolific correspondent and chronicler. His Ephemerides, spanning 1634 to 1660, and his extensive correspondence with leading thinkers across Britain and Protestant Europe offer an unparalleled window into the era's religious, political, and scientific ferment. This volume goes beyond previous studies in both scope and depth, drawing extensively on archival sources and offering new interpretations of Hartlib's network and influence. Organized chronologically, it explores the wide-ranging social, economic, and ideological pursuits of Hartlib and his collaborators-many of them renowned figures in their own right-and his close alignment with the Cromwellian cause. Providing the most complete portrait to date of the Hartlib circle's emergence and impact, this study sets a new benchmark for scholarship and invites renewed engagement with one of the early modern period's most visionary projects of knowledge, reform, and communication."--Publisher's website.