Whether Philip ever succeeded in delivering the letter is not known and he has himself been regarded as a mysterious personage of whom nothing further was known.[754] I would suggest, however, that, as he seems to have been conversant with Syria and the Holy Land, he may have been the Philip of whose translation of the _Secret of Secrets_ of the Pseudo-Aristotle we shall treat in the next chapter, a work which he found in Antioch and dedicated to the bishop of Tripoli. Or, if we do not meet this particular Philip again, we shall find in close relations with other popes other physicians whose names are prominent in the natural and occult science of the age. FOOTNOTES: [722] Berlin 956, 12th century, fols. 24-25. [723] _Gulielmi Alverni ... Opera Omnia_, 1591, p. 1003, _De universo_, II, iii, 23. [724] _Mineral._ II, iii, 4. [725] One condemned at Paris in 1277 began, “The Indians have believed....”; two in a Harleian MS 2404 are called _Indeana_; a third, part Latin and part French, in Sloane MS 314 of the 15th century, opens, “This is the Indyana of Gremmgus which is called the daughter of astronomy and which one of the sages of India wrote.” See also CU Magdalene 27 (F. 4. 27, Haenel 23), late 14th century, fols. 72-88, “Hec est geomentia Indiana que vocatur filia Ast ... quam fecit unius (_sic_) sapientum Indie....” [726] See D. E. Smith and L. C. Karpinski, _The Hindu-Arabic Numerals_, Boston, 1911; S. R. Benedict, _A Comparative Study of the Early Treatises introducing into Europe the Hindu Art of Reckoning_, Concord, 1914; L. C. Karpinski, “Two Twelfth Century Algorisms,” _Isis_, III (1921) 396-413. For “newly discovered evidence showing that the Hindu numerals were known to and justly appreciated by the Syrian writer Severus Sebokht, who lived in the second half of the seventh century,” see F. Nau in _Journal asiatique_, 1910, and J. Ginsburg, “New Light on our Numerals,” in the _Bulletin of the American Mathematical Society_, XXIII (1917) 366-9. On the question of the debt of Arabic algebra to India, especially in the case of Muhammad. b. Musa al-Hwarazmi, who was also an astrologer, see J. Ruska _Zur ältesten arabischen Algebra und Rechenkunst_, in _Sitzb. d. Heidelberger Akademie d. Wiss. Philos. hist. Klasse_, 1917. [727] _Scritti di Leonardo Pisano_, vol. I, 1857. [728] _Jordani Nemorarii Geometria vel De triangulis libri IV_, ed. M. Curtze, Thorn, 1887, pp. 43-44. [729] A good brief summary of the results of d’Avezac, Zarncke, and others will be found in Sir Henry Yule’s article on “Prester John,” EB. For the various texts to be here considered, with later interpolations and additions distinguished, see Friedrich Zarncke, _Der Priester Johannes_, in _Abhandl. d. Kgl. Sächs. Gesells. d. Wiss._ VII (1879), 627-1030; VIII (1883) 1-186.