Glass—so malleable when molten, so fragile when solid—is a metaphor for the human being. Thus the awesome words of prayer on Yom Kippur, the Day of Atonement, in which we compare G-d to a series of craftsman:
Behold, as glass in the hand of the glass-blower,
who, as he wishes forms it,
and as he wishes melts it,
so are we in Your hands,
You who forgives willful sins and inadvertent errors…[1]
Glass is melted sand. That simple statement conceals a world of historical and technological complexity. Glassmaking appears to have been invented in the vicinity of Ur, the ancient Mesopotamian city from which came Abraham, ancestor of the Jews. Like Abraham, the technology wandered westward, toward the Mediterranean Sea. It settled and flourished in the land of many names and claims: Canaan, Phoenicia, Syria, Judea, Palestine, Israel. Samuel Kurinsky provides compelling evidence for a Jewish connection to glassmaking technology.[1] Regardless of whether you accept his argument, there’s general agreement that glassmaking is a unique contribution from that much-contested part of the world.
Trade Secrets
In fact, for millennia prior to the Common Era, glass was made only in the Middle East, and nowhere else. In Egypt, Greece, and elsewhere artisans shaped glass into bowls and jars and colorful ornaments. However, chemical analysis reveals that the glass itself was manufactured in lands of Canaanite or Hebrew settlement.[2] Furthermore, ancient records reveal a commerce in raw glass ingots, shipped from the port of Akko, near present-day Haifa, to cities all along the Mediterranean coast.[3] Thus the ancient Egyptians, Greeks, Italians, and so on were glass-shapers, but not glass-makers.
Why did they have to purchase the glass they worked with? Why could they not make their own glass?
The simple answer is, they didn’t know how. They could make small amounts of glass—pretty beads or a thin glaze on pottery. But to turn a bucket of sand into a lump of glass big enough for a bowl or jug requires a furnace hot enough to melt sand. The hottest furnaces of antiquity could reach about 1300oC. Sand melts at around 1750oC. However, once the sand is formed into glass, the glass can be melted at a much lower temperature, well within reach of the ancient furnaces. Therefore, anyone who could get around the temperature problem would have a ready market for their raw glass. And not just raw glass ingots: broken glass, called cullet, was also an important resource.
The glassmakers of ancient Israel and Canaan found a way to melt sand in their existing furnaces. How did they do it? Briefly, they added to sand the ashes of plants that grew in the very salty soil of the region. Such mixtures melt at lower temperatures than the pure substances. The chemistry behind the process is discussed in the next post, “From Sand to Glass,” (click here).
Ancient glassmaking reached its peak in the region around the Belus River (now called the Na’amen), a small, muddy stream that flows out of marshes between Acco and Haifa. From here, ingots of raw glass were exported to sites all around the Eastern Mediterranean. Artisans there re-melted the glass and formed it into the various vessels and ornaments now displayed in museums as examples of “Egyptian glass,” or “Roman glass,” etc.
Breath and Form
By far the most vivid image of modern glassmaking is that of the glassblower. Using human breath he or she expands a lump of molten glass at the end of a long tube into a bubble. From there, using molds, tongs, pincers, and the like, she works the glass into the desired shape. But despite a prior thousand years of glassworking, the technique of blowing glass was only invented in about the first century BCE. The oldest known specimens of blown glass, dated to about 100 years BCE, were found in ruins in Jerusalem.[4] Before that, glass vessels were made by “core forming.” The artisan would form a mixture of clay, dung, sand and water to the shape of the interior of the desired vessel. This shape she attached to a pole, dipped it into molten glass, shaped the glass exterior, decorated it, then let it cool.
Videos courtesy The Corning Museum of Glass (Core-forming 99968; Glassblowing 714566)
After the Roman army destroyed Jerusalem, the Jewish diaspora spread northward and westward. They took glassmaking technology along with them. Some were seeking new business opportunities. Others undoubtedly were brought to Rome as slaves of the conquerors.
Meanwhile, Jewish leadership re-organized in various Israeli towns including Zippori (Sephoris) in the northern Galilee. It was there that Rabbi Yehuda HaNasi redacted the Oral Torah in the form now known as the Mishnah. Without doubt, Rabbi was familiar with the local industry of glassmaking. He found in it words of comfort for a colleague whose son had just died. He said to the grieving father, “If a vessel of glass, made by the breath of flesh and blood, when broken, can be repaired, how much more so a human being, made through the breath of the Holy One Blessed is He.”[5]
May we be worthy to stand with Moshiach, all of us repaired in flesh and spirit, at the resurrection of the dead.