This Pedro Alfonso seems to have been the same[162] who in 1106 in his forty-fourth year was baptized at Huesca with the name of his godfather, King Alfonso I of Aragon, and who wrote the _Disciplina clericalis_ and _Dialogi cum Iudeo_. Indeed we find the _Disciplina clericalis_ and _De dracone_ ascribed to him in the same manuscript.[163] In another manuscript chronological and astronomical tables are found under his name and the accompanying explanatory text opens, “Said Pedro Alfonso, servant of Jesus Christ and translator of this book.”[164] This expression is very similar, as Haskins has pointed out, to a heading in a manuscript of the _Disciplina clericalis_, “Said Pedro Alfonso, servant of Christ Jesus, physician of Henry the first (_sic_) king of the Angles, composer of this book.”[165] The experimental pretensions and astrological leanings of the astronomical treatise are suggested by Pedro’s statement that the science of the stars divides into three parts, marvelous in reasoning, notable in the signification of events, and approved in experience; and that the third part is the science of the nature of the spheres and stars, and their significations in earthly affairs which happen from the virtue of their nature and the diversity of their movements, things known by experiment. [Sidenote: His letter to the Peripatetics.] In a manuscript at the British Museum[166] I have read what seems to be a third astronomical treatise by Pedro Alfonso, differing both from the preceding and from the _De dracone_.[167] We meet as before the expression, “Said Alfonso, servant of Jesus Christ and translator of this book,”[168] and the emphasis upon experiment and astrology continues. It will be noted further that in this treatise, which takes the form of a letter to Peripatetics and those nourished by the milk of philosophy everywhere through France, Pedro is no longer connected with Englishmen, although this manuscript, too, is in an English library. After rehearsing the utility of grammar, dialectic, and arithmetic, Pedro finally comes to astronomy, an art with which “all of the Latins generally” are little acquainted, in which he himself has long been occupied, and a portion of which he presents to them as something rare and precious. It has come to his ears that some seekers after wisdom are preparing to traverse distant provinces and penetrate to remote regions in order to acquire fuller astronomical knowledge, and he proposes to save them from this inconvenience by bringing astronomy to them. Apparently, therefore, this letter to the Peripatetics and other students of philosophy is simply the advertisement of, or preface to, a translation by Pedro of some astronomical or astrological work, presumably from the Arabic.[169] It is accordingly mainly devoted to a justification of the thorough study of astronomy and astrology. Many persons, in Pedro’s opinion, are simply too lazy to take the trouble to ground themselves properly therein.