Who was the author of the Fourth Edict in the great persecution of Diocletian's reign we do not know. Its precise terms are not recorded; of the date of its issue we are not informed. It is true that Mr. Kidd has recently written: ‘On April 30, 304, Maximian put out the Fourth Edict in the name of himself and bis co-Augustus,’ but he discreetly forbears to give the reader any hint of the source on which he bases that statement. It may be doubted whether he has any better authority in mind than the ambiguous Passio S. Sabini, which, as even Mr. Mason admitted many years ago, ‘is not in the highest class of the historical relics of its age.’ If, indeed, this supposition does not do Mr. Kidd an injustice, it would have been well to have given some reasoned defence of the document. Dufourcq regards the Passio S. Sabini as a product of the Ostrogothic period, and contends that its picturesque exordium does not depend upon any earlier source. Until his detailed criticism of the Passion is answered, we can hardly use it for the reconstruction of the history of the fourth century.