If, then, a number of anecdotes in the "Secret Memoirs" are suggestive of Mrs. Haywood's known writings, and if one of them remained in her memory thirteen years later; if the pamphlet carefully alludes to Eliza Haywood as one of the dumb seer's particular friends, and if it repeats in slightly different form her peculiar account of the dumb projector's journey into Holland; and if, finally, the book contains a series of letters to Campbell from fictitious correspondents fashioned on the last already used by her, we may conclude that in all likelihood the authoress whose name had previously been associated with Duncan Campbell literature was again concerned in writing or revising this latest work. At least a cautious critic can say that there is no inherent improbability in the theory that Defoe with journalistic instinct, thinking that Campbell's death in 1730 might stimulate public interest in the wizard, had drafted in the rough the manuscript of a new biography, but was prevented by the troubles of his last days from completing it; that after his death the manuscript fell into the hands of Mrs. Haywood, or perhaps was given to her by the publishers Millan and Chrichley to finish; that she revised the material already written, supplemented it with new and old matter of her own, composed a packet of Original Letters, and sent the volume to press. The origin of the "Appendix, by Way of Vindication of Mr. Duncan Campbel" remains unknown, and any theory about the authorship of the "Secret Memoirs" must be regarded in last analysis as largely conjectural.[11a]