Painkiller: you might be interested in another book written by Robert Bartlett,
The Hanged Man: A Story of Miracle, Memory, and Colonialism in the Middle Ages. It doesn't have anything to do with levitation of Joseph of Cupertino, but it does look in depth at one miracle that was presented in the canonization hearings for a medieval saint, Thomas of Cantilupe (he resurrected a hanged man). There happens to be a lot of documentation on this case: there are the witness statements taken during the hearing. This hearing took place long after the "miracle," and there are massive discrepancies between the witness statements. In addition, there is an account that was recorded shortly after the supposed miracle at Hereford Cathedral, whence many of the witnesses had gone in thanksgiving. That account is used to check the statements made many years later during the canonization hearing. It gives an idea of how miracle stories can develop.
