The literary history of Byron’s fragmentary novel and of Polidori’s short story, The Vampyre, is somewhat tangled, but the solution is to be found in the diary of Dr. John William Polidori, edited and elucidated by William Michael Rossetti.  The day after that on which Polidori states that all the competitors, except himself, had begun their stories, he records the simple fact:  “Began my ghost-story after tea.”  He gives no hint as to the subject of his tale, but Mrs. Shelley tells us that Polidori had some idea of a “skull-headed lady, who was so punished for looking through a key-hole, and who was finally buried in the tomb of the Capulets.”  In the introduction to Ernestus Berchtold, or the Modern OEdipus, he states definitely: 

“The tale here presented to the public is one I began at Coligny, when Frankenstein was planned, and when a noble author, having determined to descend from his lofty range, gave up a few hours to a tale of terror, and wrote the fragment published at the end of Mazeppa.”

As no skull-headed lady appears in Ernestus Berchtold, it is probable that her career was only suggested to the rest of the party as an entrancing possibility, and never actually took shape.  This theme would certainly have proved more frightful and possibly more interesting than the one which Polidori eventually adopted in Ernestus Berchtold, a rambling, leisurely account of the adventures of a Swiss soldier, whose wife afterwards proves to be his own sister.  Their father has accepted from a malignant spirit the gift of wealth, but each time that the gift is bestowed some great affliction follows.  This secret is not divulged until we are quite near the close of the story, and have waited so long that our interest has begun to wane. Ernestus Berchtold is, as a matter of fact, not a novel of terror at all.  The supernatural agency, which should have been interlaced with the domestic story from beginning to end, is only dragged in because it was one of the conditions of the competition, as indeed Polidori frankly confesses in his introduction: 

“Many readers will think that the same moral and the same colouring might have been given to characters acting under the ordinary agencies of life.  I believe it, but I agreed to write a supernatural tale, and that does not allow of a completely everyday narrative.”

The candour of this admission forestalls criticism.  Strangely enough, Polidori adds that he has thrown the “superior agency” into the background, because “a tale that rests upon improbabilities must generally disgust a rational mind.”  With so decided a preference for the reasonable and probable, it is remarkable that Polidori should treat the vampire legend successfully.  It has frequently been stated that Byron’s story was completed by Polidori; but this assertion is not precisely accurate.  Polidori made no use of the actual fragment, but based