His motive and his personality still remain matters of conjecture.

Whether the whole affair was a figment of Shelley's brain, rendered more than usually susceptible by laudanum taken to assuage intense physical pain; whether it was a perilous hoax played upon him by the Irish servant, Daniel Hill; or whether, as he himself surmised, the crime was instigated by an unfriendly neighbour, it is impossible to say.

Strange adventures of this kind, blending fact and fancy in a now inextricable tangle, are of no unfrequent occurrence in Shelley's biography.

In estimating the relative proportions of the two factors in this case, it must be borne in mind, on the one hand, that no one but Shelley, who was alone in the parlour, and who for some unexplained reason had loaded his pistols on the evening before the alleged assault, professed to have seen the villain; and, on the other, that the details furnished by Harriet, and confirmed at a subsequent period by so hostile a witness as Eliza, are too circumstantial to be lightly set aside.
On the whole it appears most probable that Shelley on this night was the subject of a powerful hallucination.

The theory of his enemies at Tanyrallt, that the story had been invented to facilitate his escape from the neighbourhood without paying his bills, may be dismissed.