Gerald of Wales, who was proud of all his literary output, was clearly particularly proud of the Gemma Ecclesiastica. With typically false self-deprecation he wrote in the preface that if perhaps the work should cross the Anglo-Welsh border and fall into the hands of the great, and be seen by the eyes of the learned, he would prefer that they read what they knew already than that his Welsh readership should be deprived. And in a famous passage in his autobiography he tells how when he visited Rome in 1199 he presented Pope Innocent III with six of his books – libros rather than libras (pounds) – and that the pope kept all the volumes at his bedside for about a month before distributing five of them to five of his cardinals who requested them, but he would not allow himself to be parted from the Gemma, which he loved above all the rest. By reciting Innocent’s approbation it is as if Gerald was granting himself an imprimatur from the greatest of all medieval reforming popes. Yet, compared with many other of Gerald’s works, notably the topographical, historical and autobiographical ones, the Gemma has received little attention from commentators. It was edited, and published in 1862, in the Rolls Series by J. S. Brewer who provided a lengthy introduction, and a translation with introduction by John Hagen appeared in 1979 as The Jewel of the Church. As is the case with a work which can in many ways be seen as its sister volume, the Speculum ecclesie, there have been no major studies of the Gemma. Though it was apparently little read, when set within the context of Paris-inspired developments in pastoral theology, it is an important indicator of reforming preoccupations at a time of unprecedented concern for the spiritual wellbeing of clergy and laity alike, as typified in England by Thomas of Chobham’s Summa Confessorum.

The Gemma is the earliest of a trio of explicitly didactic works that also include the De principis instructione and the Speculum ecclesie. It is probably to be dated to c. 1197 and the De principis instructione to some time before c. 1217; the Speculum was not completed till 1219 at the earliest.