Throughout the book the historical precedents of the type of glass under discus-sion are referenced, but it may be helpful to give a brief overview here as well.
Though it is not clear how the invention of glass occurred, it is thought that glass was first made around 3000 BCE in Mesopotamia. Medieval and Renais-sance perceptions of the medium’s invention were influenced by Isidore of Seville’s Etymologies, which describes how travelling merchants accidentally discovered how to make glass while camping on a sandy bank of the Belus River in Syria.
Unable to find rocks to support their kettles, the merchants used natron from the
ship’s cargo. When they started the fire, the combination of natron, fire, and the pure sands of this region produced the first instance of glass.17
Some of the earliest extant Egyptian glass is opaque and was made using either the core-formed technique or by using a mold. Typical examples of the types of glass object include glass beads, bottles, other small containers, mosaic glass, and glass inlays for jewelry or furniture. As would be the case with glass throughout much of its history, the shapes, colors, and functions of the earliest glass objects suggest that these products were made in imitation of other materials, primarily precious stones or minerals. In fact, when Isidore of Seville describes the different colors of glass, he compares them to sapphires, onyx, and other gemstones.
Ancient Greek glass production, though slow at first, peaked during the Clas-sical and Hellenistic periods. Not many glass vessels have been recovered from Mycenaean Greece, and the few objects that have been found suggest that at this time Greece did not have its own glass-production centers but rather imported premade glass from Egypt. Most of the objects, which consist of pendant-like ornaments and small figures dating from ca. 1300 BCE, were made from a bright translucent blue glass that matched the chemical composition of contemporane-ous Egyptian glass.18
Glass production in Classical and Hellenistic Greece grew and emulated the Egyptian model in terms of technique and products until about the third century BCE. Burial finds suggest that early Greek glass objects were brightly colored vials with small openings used for the storage of perfume made using the core-formed technique and meant to imitate more precious materials.19 By the mid-third century BCE, a more characteristically Greek glass industry had developed.
Craftsmen developed new techniques such as network glass and mosaic glass, the latter of which was often used to make plates or bowls by fusing together many multicolored canes to form a complex and intricate spiral pattern.20 It was also at this time that clear glass and gold sandwich glass developed, a topic treated in more detail in Chapter 3.21
It was in imperial Rome where glass production, of both colored and trans-parent glass, reached its zenith.22 Glass was used in a variety of different ways in ancient Rome; it was fashioned into expensive luxury items like jewelry and lavish furniture inlays and used for household utilitarian storage containers, win-dows, and mirrors.23 The Romans could create a vast range of objects because they had many different methods of working with glass available to them. The most revolutionary technique used in the production of ancient Roman glass was the blown-glass technique, which was developed near Syria in the first century BCE.24 The Roman glass industry flourished as craftsmen refined the techniques
of blowing, painting, engraving, gilding, and casting glass and, in so doing, pro-vided long-lasting inspiration for the re-emergence of the glass industry in the Levant and the Latin West.25
The Byzantine and Islamic glass-making centers in the East preserved the Roman knowledge base and cultivated specifically eastern innovations in style and technique. Their fine luxury products, particularly lamps and so-called per-fume jars, became highly valued commodities on the trade circuits, but these glass objects could also take on special religious significance, as seen in the case of pilgrim flasks. As discussed in Chapter 4, one of the main ways these glass bottles entered the Latin West was as reliquaries carried home from the Holy Land by religious pilgrims. The importation and inspiration of such objects, along with the import of cullet—pieces of broken glass that could be melted down and refashioned into new objects—as well as the arrival of glassworkers from the East, dramatically re-energized the production of glass in the West.
After the fall of Rome, glass production in the Latin West slowed consid-erably, but it did not die out entirely. While it is true that very few examples of medieval glass exist, Alan Macfarlane and Gerry Martin contend that the lack of archeological evidence supporting medieval glass manufacture is due to changes in medieval burial customs and glassmaking practices.26 Oftentimes glass objects were interred with their owners and thus protected from centuries of handling.
Tombs were effective time capsules, protecting fragile glass objects from destruc-tion. However, with the rise of Christianity, burial customs changed. Christians did not regularly bury objects along with their deceased, effectively eliminating one of the main methods for preserving glass objects.27 Also contributing to the decreased survival rate was the fact that, during the medieval period, glassworkers began melting and reusing glass objects to a greater degree. Furthermore, crafts-men began making their glass with potash from woodland plants instead of from sea plants, as was common practice in the Mediterranean region. The potash obtained locally from the woodland plants was more readily available, but the glass it produced was more prone to decay.
Venice was home to one of the most robust glassmaking centers in medieval Europe, an important point for a study of Italian glass. The Venetian glass tradition reached its peak in terms of skill and market value during the later Renaissance period, but, due to its connections with the Levant, it was already flourishing by the thirteenth century. It was also during the thirteenth century that we find some of the earliest Italian churches incorporating stained glass, with one of the most famous examples at San Francesco in Assisi. The next chapter will look more closely at the phenomenon of stained glass in an Italian context.
Notes
1. Vincent Ilardi, Renaissance Vision from Spectacles to Telescopes (Philadelphia: American Philosophical Society, 2007), 38.
2. Samuel Y. Edgerton, The Mirror, the Window, and the Telescope: How Renaissance Linear Perspective Changed Our Vision of the Universe (Ithaca, NY: Cornell University Press, 2009), 6.
3. Alessandro Bagnoli, La Maestà di Simone Martini (Milan: Silvana Editoriale, 1999).
4. It should be noted that Kessler does consider other reflective materials as substitute mate-rials for glass mirrors. See Herbert Kessler, “Speculum,” in Speculum 86 (2011): 10.
5. David C. Lindberg, Theories of Vision from Al-Kindi to Kepler (Chicago: University of Chicago Press, 1976), 87–90.
6. Ibid., 91–102.
7. Ibid., 92.
8. Ibid., 104–5.
9. David C. Lindberg notes, “In place of these discredited theories, [Albert] attempts to establish the Aristotelian doctrine that vision is caused by an alteration (immutatio) of the transparent medium by the visible object and the propagation of this alteration to the watery substance of the eye.” See ibid., 105.
10. Lindberg, Theories of Vision, 109, 112. For more on Roger Bacon, see John Henry Bridges, The “Opus Majus” of Roger Bacon (Cambridge: Cambridge University Press, 1964); David C. Lindberg, Roger Bacon’s Philosophy of Nature (Oxford: Oxford University Press, 1983); and David C. Lindberg, Roger Bacon and the Origins of Per-spectiva in the Middle Ages (Oxford: Oxford University Press, 1996). For the most influential theorists preceding Bacon—that is (in chronological order), Seneca, Pliny the Elder, Chalcidius’s translation of Plato’s Timaeus, Augustine, William of Conches, Robert Grosseteste, and Albertus Magnus—see Lindberg, Theories of Vision, 87–107.
For more on the most significant optical treatises of the fourteenth century, see ibid., 122–46. Albertus achieved a similar feat just before Bacon but did not fully integrate Alhazen.
11. Ibid., 109.
12. Ibid., 111–12.
13. Lindberg, Theories of Vision, 161.
14. Alan Macfarlane and Gerry Martin note, “He looked at various curved surfaces and the principles of refraction and reflection from these surfaces, using concave and convex mirrors. He looked at clear mirror images to see how the image is reflected in the mirror. Mirrors, prisms and lenses allowed the new mathematics and geometry to develop.” See Alan Macfarlane and Gerry Martin, Glass: A World History (Chicago:
University of Chicago Press, 2002), 42.
15. Robert Belle Burke, The “Opus Majus” of Roger Bacon, vol. 2 (Whitefish, MT:
Kessinger Publishing, 2002), 546–57.
16. Ibid., 553–57. In one such example, Bacon described that when “the eye is at the center of a concave mirror, it is the only thing visible to itself; for no form is reflected to the center except that which comes from the center. The perpendicular, in fact, returns upon itself.” Ibid., 555.
17. Stephen A. Barney and others, eds., The Etymologies of Isidore of Seville (Cambridge:
Cambridge University Press, 2010), 328.
18. Hugh Tait, ed., Five Thousand Years of Glass (London: British Museum Press, 1991), 24–25.
19. Jennifer Price, “Glass,” in A Handbook of Roman Art, ed. Martin Henig (London and New York: Phaidon Press, 2006), 205.
20. Tait, Glass, 48.
21. Ibid., 49. For more details on the other types of developments at this time see ibid., 50–61.
22. As Jennifer Price notes, during Roman times glass “exerted a greater influence on daily life than at any other period before the Renaissance.” See Price, “Glass,” 205. As Alan Macfarlane notes, “Roman glass technology was in many ways unrivalled until the nineteenth century.” See Macfarlane and Martin, Glass, 13.
23. Macfarlane and Martin, Glass, 15–16.
24. Macfarlane and Martin, Glass, 13; Price, “Glass,” 205–7.
25. The influence of Roman gold glass on later medieval glass is discussed further in Chapter 3.
26. Macfarlane and Martin, Glass, 19–21.
27. For exceptions describing some glass vessels from Christian burial sites, see David Whitehouse, Medieval Glass for Popes, Princes, and Peasants, with contributions by William Gudenrath and Karl Hans Wedepohl (Corning, NY: Corning Museum of Glass, 2010), 56.
References
Bagnoli, Alessandro. La Maestà di Simone Martini. Milan: Silvana Editoriale, 1999.
Barney, Stephen A., W. J. Lewis, J. A. Beach, Oliver Berghof, trans. The Etymologies of Isidore of Seville. Cambridge: Cambridge University Press, 2010.
Bridges, John Henry, ed. The “Opus Majus” of Roger Bacon. Cambridge: Cambridge University Press, 1964.
Burke, Robert Belle. The “Opus Majus” of Roger Bacon. Vol. 2. Whitefish, MT: Kessinger Publishing, 2002.
Edgerton, Samuel Y. The Mirror, the Window, and the Telescope: How Renaissance Linear Perspective Changed Our Vision of the Universe. Ithaca, NY: Cornell University Press, 2009.
Ilardi, Vincent. Renaissance Vision from Spectacles to Telescopes. Philadelphia: American Philosophical Society, 2007.
Kessler, Herbert. “Speculum.” Speculum 86 (2011): 1–41.
Lindberg, David C. Theories of Vision from Al-Kindi to Kepler. Chicago: University of Chicago Press, 1976.
———. Roger Bacon’s Philosophy of Nature. Oxford: Oxford University Press, 1983.
———. Roger Bacon and the Origins of Perspectiva in the Middle Ages. Oxford: Oxford University Press, 1996.
Macfarlane, Alan, and Gerry Martin. Glass: A World History. Chicago: University of Chicago Press, 2002.
Price, Jennifer. “Glass.” In A Handbook of Roman Art, edited by Martin Henig, 205–19. London and New York: Phaidon Press, 2006.
Tait, Hugh, ed. Five Thousand Years of Glass. London: British Museum Press, 1991.
Whitehouse, David. Medieval Glass for Popes, Princes, and Peasants. Corning, NY: Corning Museum of Glass, 2010.