One of the most significant occurrences in the history of design was the creation of the English Landscape Garden. Accounts of its genesis the surprising structural change from the formal to a seeming informal are numerous. But none has ever been quite convincing and none satisfactorily placed the contributions of Stephen Switzer.

Unlike his contemporaries, Switzer - an 18th century author of books on gardening and agricultural improvement - grasped a quite new principle: that the fashionable pursuit of great gardens should be "rural and extensive," rather than merely the...