This much-needed book is now the definitive biography of John Erskine, one of the most influential pastors and theologians in eighteenth-century Scotland. Yeager convincingly argues that Erskine was a proponent of moderate Enlightenment thought as well as orthodox Calvinism. But Erskine's chief influence is not suggested by the book's title. According to Yeager, Erskine was the ‘leading disseminator of evangelical Calvinism in the eighteenth century’ (p. 196).

That is quite a claim, but it is backed up by Erskine's remarkable devotion to the distribution of books, sermons and pamphlets across Britain and America. He not only loved books himself – his own library totalling nearly 4,000 volumes at his death – but he sent vast numbers of them to associates. Yeager tells us that Erskine posted a parcel of publications along with almost all his letters, presumably at enormous personal expense. On average, he sent about four to eight books with each letter. Some correspondents ultimately received dozens of letters and hundreds of books: for example, Erskine's extant letters show that he sent the Baptist John Ryland, Jr. at least 400 printed items over the course of several decades.

Erskine's relationship with Jonathan Edwards, the brilliant pastor-theologian of Northampton, Massachusetts, is a major highlight of Yeager's book. To say that Erskine's theology did not match the soaring insights of Edwards’ is hardly to denigrate Erskine. Indeed, Erskine had a bit of a disagreement with Edwards theologically over the place of the will in the choice of salvation, but as Yeager explains, Erskine may not have fully understood Edwards’ argument in Freedom of the Will (again, no great indictment of Erskine). Unlike Edwards, who emphasised God's transformation of the will in saving the elect, Erskine entirely de-emphasised the will's role in salvation. He argued that ‘saving faith is the revelation that Jesus is the Son of God and Savior of the elect’ (p. 99). Yet Erskine overlooked this disagreement and became not only Edwards’ chief bibliographical supplier, but the most ardent propagator of Edwards’ ideas in the decades after the New Englander's death.

In these practical ways, Edwards depended heavily on Erskine, both in his intellectual development and in the preservation of his theological legacy. In the extant correspondence between them, Edwards acknowledged receiving almost sixty publications from Erskine, but the total could have run into the hundreds. One estimate suggests that a third of Edwards’ personal library was composed of gifts from Erskine. Many of these books, surprisingly, were Deistic or otherwise heterodox, sent with the hope that Edwards would challenge them in print. When Edwards was dismissed from his Northampton congregation, Erskine suggested the possibility of finding him a church in Scotland. That move did not transpire, but their connection was as deep intellectually as one could reasonably forge with a correspondent across the ocean in the era of pre-electronic communication.

In Erskine, then, we find the evangelical disseminator par excellence in the eighteenth century's republic of letters. Recommending and gifting books was a common practice of Edwards, George Whitefield, the Wesley brothers and other evangelical leaders, but no one went to the lengths of Erskine. He even learned Dutch and German at the age of 60 in order to extend the reach of his reading and correspondence on the Continent. The literature on eighteenth-century evangelicalism has established the way in which the ‘community of saints’ was partly created by new publishing networks and evangelical magazines in Boston, London and Glasgow. But Yeager takes this understanding one step further to show how individuals – none more than Erskine – could profoundly shape the evangelical movement by their personal dissemination of those printed goods.