Robert Recorde was an important sixteenth-century Welsh physician and mathematician and one of the most enigmatic figures of Tudor England. This book presents a richly detailed and fully rounded picture of Recorde as an academic, theologian, astronomer, antiquarian, inventor of the "equals" sign (=), and writer of widely used textbooks. He was also a scholar who found himself completely out of depth in surrounding political and religious dramas. Drawing from numerous extracts from Recorde's own writings transcribed into modern English, Gordon Roberts offers the first full-length biography of an intellectual at the center of intrigue and turmoil.