Leonardo da Vinci's portrait of Cecilia Gallerani captures the beauty and youth of the mistress of Ludovico Sforza, Duke of Milan (figure 1). Cecilia was admired in Sforza circles for her charm and her skill as a writer in both Latin and Italian, and she held a leading place at court until Ludovico's marriage to Beatrice d'Este in 1491. After some early and unfounded hesitation concerning the authorship, the attribution to Leonardo has gained universal acceptance, as has the identification of the sitter as Cecilia.1 For some basic literature on the portrait, see Emil Möller, ‘Leonardos Bildnis der Cecilia Gallerani in der Galerie des Fürsten Czartoryski in Krakau’, Monatshefte für Kunstwissenschaft, 9 (1916), pp. 313–26; Kenneth Clark, Leonardo da Vinci (Harmondsworth: Penguin, 1959), pp. 54–5; Carlo Pedretti, Leonardo: A Study in Chronology and Style (New York-London: Thames & Hudson, 1973), pp. 65-7; Jack Wasserman, Leonardo (New York: Abrams, 1984), p. 136; Martin Kemp, cat. entry in Circa 1492: Art in the Age of Exploration, ed. Jay Levenson (New Haven: Yale University Press, and Washington, DC: National Gallery of Art, 1991), pp. 271–2; Józef Grabski and Janusz Wałek, eds, Leonardo da Vinci (1452–1519): ‘Lady with an Ermine' from the Czartoryski Collection, National Museum, Cracow (Vienna-Cracow: IRSA, 1991), passim, and the essay there by Marek Rostworowski, ‘Leonardo da Vinci's Lady withan Ermine’, pp. 19–23; David Bull, ‘Two Portraits by Leonardo: Ginevra de' Benci and the Lady with an Ermine’, Artibus et Historiae, 13/25 (1992), pp. 67–83; Maria Rzepińska, ‘Lady with the Ermine Revisited’, Achademia Leonardi Vinci: Journal of Leonardo Studies and Bibliography of Vinciana, 6, (1993), pp. 191–9; Krystyna Moczulska, ‘Najpiekniejsza Gallerian i najdoskonalsza Galle w portrecie namalowanym przez Leonardo da Vinci’, Folia Historiae Artium, new series 1 (1995), pp. 55–86; Pietro Marani and Barbara Fabjan, Leonardo: La dama con l'ermellino (Milan: Silvana, 1998), esp. Marani's ‘Scheda storico-artistica’, pp. 76–82; Dorota Dec, catalogue entry in Laurie Winters, ed., Leonardo da Vinci and the Splendor of Poland: A History of Collecting and Patronage (New Haven: Yale University Press, for the Milwaukee Art Museum, 2002), pp. 156–9. For the dating of Cecilia's costume, which is Spanish in influence and is widely believed to have been in use in Italy only towards 1490, see Zdzislaw Żygulski, Jr., ‘Costume Style and Leonardo's Knots in the Lady with an Ermine, 'in Grabski and Wałek, eds, Leonardo da Vinci (1452–1519): ‘Lady with an Ermine’, pp. 24–7. She herself referred to the portrait in 1498 when she lent it to Isabella d'Este, Marchesa of Mantua, noting in a letter that she was ‘immature’ at the time of the sitting and no longer resembled it, a statement implying some passage of time between the making of the work and 1498. Indeed, the portrait was celebrated in a contemporary sonnet by the Milanese humanist Bernardo Bellincioni, whose death in September 1492 provides a terminus ante quem for the painting, which Leonardo made when Cecilia was no more than 19.2 For the letters between Cecilia and Isabella, see Adolfo Venturi, ‘Nuovi documenti su Leonardo da Vinci’, Archivio storico dell'arte, I (1888), p. 45, and Alessandro Luzio, ‘Ancora Leonardo da Vinci e Isabella d'Este’, Archivio storico dell'arte; I (1888), p. 181. Janice Shell and Grazioso Sironi provided biographical information concerning Cecilia and Ludovico, and argued that the date of the work falls to about 1489–1490.3 Janice Shell and Grazioso Sironi, ‘Cecilia Gallerani: Leonardo's Lady with an Ermine’, Artibus et Historiae, 13/25 (1992), pp. 47–66. While the attribution, identity of the sitter and approximate date are now established, some aspects of the meaning of the work are in dispute, and nearly all of the trouble is caused by the lively animal that the young lady holds in her hands.