This is the first volume of a six volume compendium on the correspondences of John Wallis (1616-1703). Wallis was Savilian Professor of Geometry at Oxford from 1649 until his death, and was a founding member of the Royal Society and a central figure in the scientific and intellectual history of England. Along with his role as decipherer on the Parlimentary side during the Civil War, he prepared the ground for the discovery of infinitesimal calculus by Newton and Leibniz and played a decisive role in modernization of English mathematics. This volume provides fascinating insight into the life of Wallis through his correspondences with intellectual and political figures of the latter part of the 17th century.