The aim of this thesis is to examine the history of the transmission of the ideas of St John of the Cross during the early years of the seventeenth century. Thomas of Jesus is shown to have exercised a profound and detrimental influence over this transmission both by his early, unfulfilled commission to prepare a first edition of St John's works and, more significantly, by the use he made of the saint's doctrines in his own descriptions of prayer and the subsequent absorption of his ideas into the Carmelite school of spirituality. Father Salablanca was responsible for the numerous textual alterations to St. John's works in their first edition. His interventions are found to have misrepresented key aspects of St John's system, an influence which persisted for almost three hundred years, until the first critical edition appeared in 1912. Despite precautions taken by Salablanca, the sect of the alumbrados in Seville derived many of its doctrines from St John's works. This thesis reveals the correspondence between the Sevillian Inquisition and the Inquisitor General relating to the involvement of the 1618 edition with the alumbrados. The defence made of St John's works by Basilio Ponce de Leon is discussed. It is found that this defence relies largely on the textual amendments introduced by Salablanca and on doctrinal accommodations similar to those initiated by Thomas of Jesus. Therefore, while accomplishing its immediate aim, the defence was to reinforce the flawed image of St John's ideas which had been promoted by St John's editor and earliest commentators. The coincidence of themes misrepresented by Thomas of Jesus, amended by Salablanca, adopted by the alumbrados and censured by the Inquisition is finally taken to indicate the areas where St John made innovative contributions to the field of spirituality.