The first volume of several to be devoted to Latin church music by composers of the late fifteenth and early sixteenth centuries, EC43 contains all that survives of Fayrfax's O bone Iesu trilogy. From the material shared between the Mass and antiphon (an early example of English parody technique) it has been possible to reconstruct part of the latter, of which only the mean survives. In addition, the Appendix contains the conclusion of a fragmentary composition from the Jena Choirbook.