Both are in Latin, and are fairly transcribed on vellum in contemporary hands, with diagrams upon the margin.[147] The former is entitled _De Perspectiva_, but the subject is, in fact, Light,[*148] and its effect upon objects and colours. In place of a general title, it sets out with a dictum that "light is to philosophical inquiry what demonstrative certainty is to mathematics." The volume, bearing the arms and initials of Duke Federigo, must have been written for his library: though anonymous, it is clearly the work referred to in a dedication which we shall presently quote, the only other MS. upon perspective in the collection being that by Vitellioni (No. 265). [Footnote *144: Cf. PICHI, _La Vita e le Opere di Piero della Francesca_ (Borgo S. Sepolcro, 1893); WITTING, _Piero dei Franceschi_ (Strassburg, 1898); CROWE & CAVALCASELLE, _op. cit._, vol. III. BERENSON, _op. cit._, p. 69, says: "The pupil of Domenico Veneziano in characterisation, of Paolo Uccello in perspective, himself an eager student of this science, as an artist he [Piero] was more gifted than either of his teachers." Fra Luca Pacioli, one of the finest mathematicians of his day, praises Piero, and speaks of his renowned treatise on perspective, "now in the library of our illustrious Duke of Urbino."] [Footnote *145: Cf. on this point MUNTZ, _Precursori e propugnatori del Rinascimento_ (Firenze, 1902), p. 59 _et seq._ For his life _Vita Leonis Baptistae de Albertis_, by an anonymous author, believed to be Alberti himself, in MURATORI _R.I.S._, vol. XXV., partly translated in EDWARD HUTTON, _Sigismondo Malatesta_ (Dent, 1906), pp. 163-9. Cf. also MANCINI, _Vita di L.B.A._ (Firenze, 1882), and _Nuovi documenti e notizie sulla vita e gli scritti di L.B.A._, in _Arch. St. It._, Series IV., vol. XIX.; also SCIPIONI, in _Giornale St. d. Lett. Ital._, vol. II., p. 156 _et seq._, and vol. X., p. 255 _et seq._] [Footnote *146: This is a tale like so much in Vasari. Piero was never blind at all it seems. BOSSI, in his work on Leonardo's _Cenacolo_ (Milan, 1810), deals minutely with this libel.]