This book is a study of the contribution of Isaac Barrow (1630-1677), Master of Trinity College (Cambridge), to Western perceptions of Islam in the 17th century. In particular, it provides a translation and study of Barrow's Latin essay on Islam (written in Constantinople), a Sermon on Islam and several other works that set out an embryonic theory of religion. Arguably, Barrow's writing on Islam is the first by a mainstream English scholar to move away from total hostility toward an empathetic approach that contemplated the possibility of salvation for Muslims. His work contributes to contemporary dilemmas and challenges on the nature of religion.