 The latter series contained editions of the correspondence and "vitae" of Saint Boniface; his edition of the Boniface correspondence was praised as the first critical edition of the letters, and formed the basis for subsequent translations and editions of the letters, including that by Georg Pfahler.Jaffé furthermore collaborated with Wilhelm Wattenbach in editing the "Ecclesiæ Metropolitanæ Coloniensis Codices," which was published (Berlin, 1879) by Wattenbach after Jaffé's death.Jaffé committed suicide at Wittenberge on April 3, 1870.