In the intellectual change that took place in the seventeenth century, the role of Samuel Hartlib was of immense significance. As John Milton put it, he was sent 'hither by some good providence from a farre country to be the occasion and the incitement of great good to this Hand'. Hartlib (originally from Elbing) settled in England in the late 1620s and lived there until his death in 1662. His aspirations formed a distinctive and influential strand in English intellectual life during those revolutionary decades. This volume reflects the variety of the theoretical and practical interests of Hartlib's circle and presents them in their continental context. The editors of the volume are all attached to the Hartlib Papers Project at the University of Sheffield, a major collaborative research effort to exploit the (largely untapped) resources of the surviving Hartlib manuscripts. In an introduction to the volume they explore the background to the Hartlib circle and provide the context in which the essays should be read.