Although a tribunal has existed for more than three hundred years in Spain, invested with the power of prosecuting heretics, no correct history of its origin, establishment, and progress has been written. Writers of many countries have spoken of Inquisitions established in different parts of the world, where the Roman Catholic faith is the religion of the state, and yet not one is worthy of confidence. The work of M. Lavallée, entitled the "History of the Inquisitions of Italy, Spain, and Portugal," and published in 1809, has only added to the historical errors of the authors who preceded him. The Spanish and Portuguese writers on the same subject deserve no higher credit; and have not detailed, with accuracy, the circumstances which led to the establishment of this dreadful tribunal. These writers even differ in their statements of the period of its origin, and place it between the years 1477 and 1484. One affirms, with confidence, that the latter date is the true one, because in that year the regulations of the tribunal were enacted; another decides that it originated in 1483, because in that year Thomas Torquemada was appointed inquisitor-general by the Pope. The inquisition of Spain was not a new tribunal created by Ferdinand V. and Isabella, the queen of Castile, but only a reform and extension of the ancient tribunal, which had existed from the thirteenth century. No one could write a complete and authentic history of the Inquisition, who was not either an inquisitor or a secretary of the holy office. Persons holding only these situations could be permitted to make memoranda of papal bulls, the ordinances of sovereigns, the decisions of the councils of the "_Suprême_," of the originals of the preliminary processes for suspicion of heresy, or extracts of those which had been deposited in the archives. _Being myself the secretary of the Inquisition at Madrid_, during the years 1789, 1790, and 1791, I have the firmest confidence in my being able to give to the world _a true code of the secret laws by which the interior of the Inquisition was governed, of those laws which were veiled by mystery from all mankind_, excepting those men to whom the knowledge of their political import was exclusively reserved. A firm conviction, from knowing the deep objects of this tribunal, that it was vicious in principle, in its constitution, and in its laws, notwithstanding all that has been said in its support, induced me to avail myself of the advantage my situation afforded me, and to collect every document I could procure relative to its history. My perseverance has been crowned with success far beyond my hopes, for in addition to an abundance of materials, obtained with labour and expense, consisting of unpublished manuscripts and papers, mentioned in the inventories of deceased inquisitors, and other officers of the institution, in 1809, 1810, and 1811, when the Inquisition in Spain was