Moses was a spiritual genius. He spoke with G-d face-to-face. He recorded G-d’s words in a timeless document, the Torah. The Divine Presence spoke through his mouth. Yet when G-d gave him the details for building a menorah—a candlestick of seven lamps—Moses, according to a Midrash, did not understand how to proceed.
G-d’s instructions were minutely detailed. You shall make a Menorah of pure gold, of beaten-work it shall be made…six branches going out of its sides…[with ornamental] cups…and knobs…and flowers…of a kikar (about 100 pounds) of pure gold he shall make it…after the pattern shown to you [Moses] on the Mountain.[1]
But, Moses wondered, how could a heavenly vision be expressed through earthly materials? G-d then said, throw the kikar of gold into the fire and it will be made of itself (miraculously).[2]
Other traditions hold that the Menorah was made by Betzalel. He was the master craftsman who oversaw all the work of the Mishkan (the sanctuary or “tabernacle” built by the Jews after leaving Egypt). The great medieval commentator Rabbi Shlomo Yitzhaki of Troyes (Rashi) explains, “He beat it with the hammer and cut away with the implements of his craft, thus making the branches spread out in this direction and in that.”[3]
Modern students of Torah might be as puzzled as Moses, although for different reasons. Pure gold is famously soft. It is malleable, meaning that it flattens and bends readily under pressure. It’s also ductile, meaning that it can be stretched thin without breaking. In fact, gold is the most malleable and ductile of all metals. It can be beaten or stretched into a foil so thin that more than two hundred sheets of gold foil laid on top of each other would be only as thick as a human hair![4]
Gold is very dense. A kikar of pure gold would amount to a cube only about thirteen centimeters (about five inches) on each side. Perhaps the kikar meant here was the sacred kikar, which is twice the weight of the everyday measure.[5] If so, its volume would fill a cube only seventeen centimeters (six and a half inches) on each side. The menorah stood over 1.6 meters tall. Its six branches stretched out on either side, with elaborate decorations hammered into their lengths. Even if the menorah were hollow (it probably was) how could such a huge, complex shape be just by hammering, and out of such a comparatively small block of gold? And given the softness of gold, wouldn’t the finished product dent or bend too easily for practical use?
Thus the question: Is a menorah of pure gold physically feasible? Or could the first menorah only have been made by a miracle, as the Midrash asserts?
A basic goal of Jewish life is to elevate nature by using it to serve G-d. Therefore, we don’t resort to miracles when nature can do what’s needed. So the question becomes whether a practical menorah could have been made using metal-working methods known at the time of the Exodus.
I’m not sure, but I think the answer is yes.
To understand, let’s consider what makes pure gold so uniquely malleable, and how its finished surface can be hardened.
The Mystery of Malleability
Hit a diamond with a hammer and it shatters. Hit a piece of gold or red-hot steel with a hammer and it flattens, but stays intact. The difference between diamond and metal is due to how the atoms bond together to make a solid piece. This depends on the nature of the atoms themselves.
Most solids are built of atoms arranged in orderly, repeating patterns. (Think of the patterns on decorative wrapping paper.) Electrons, the outermost and negatively charged part of atoms, form the “glue” that binds one atom to another. Whether a substance is brittle and breaks easily, or is malleable, depends on how the electrons are arranged. (For a review of atomic structure and electric charge, click here.)
Atoms of brittle solids, like diamond or quartz, bond by sharing their outermost electrons only with their immediate neighbor atoms. A sharp blow, as from a hammer, pushes a row of atoms out of their positions. The bonds stretch to the breaking point, and the lump of material shatters. But bonding in metal is a
Electrons [pale blue] in brittle solid [left] and metal[right]
Since atoms by themselves have equal numbers of positively and negatively charged particles, atoms that have given up some (negative) electrons are left with an excess of positive charge. Thus you can picture a solid piece of metal as made of evenly-arranged positive charges awash in a “sea” of negative charge. In fact, this picture of metallic bonding is called the “electron sea” model.
Like water, the “electron sea” can slosh around to accommodate changes of environment. If a hammer-blow forces a row of positively charged atoms to move, the electrons move along with them. Charges that are the same repel each other. Opposite charges attract. Since the metal atoms are positively charged, they repel each other. Their usual arrangement in a solid is a compromise between repulsion from neighboring atoms above, below, and all around. When atoms slide past other atoms, the compromise is disrupted. The charged atoms come repulsively close. But attraction from the electron sea shields the atoms from the full repulsion. When the hammer is lifted, the displaced atoms re-adjust to their ideal arrangement, but with new atomic neighbors.
The electron sea model explains metallic malleability. But it doesn’t explain differences between metals. Differences depend on particulars such as symmetry of atomic arrangement, atom size, and effective nuclear charge. None of these factors explain what makes gold the most malleable of all metals. To answer that requires a closer look at what happens to metals under hammering.
Adventures in Hardening
I’ve never handled pure, 24-carat gold. However, I have worked with pure silver, a metal nearly as malleable as gold. The silver in question was a thick wire, about two millimeters diameter. I wound it into a coil to be used as an electrode in a chemical application.
At first the wire bent easily under my fingers. However, as I shaped the coil, I could feel the metal growing harder and stiffer.
I was experiencing what metal workers have known for thousands of years: metals grow harder and more brittle the more they are “worked.” The process is called (appropriately) work-hardening. Should a metal piece become too hard as it is forced into a new shape, malleability can be restored by heating it, a process called annealing.
Work-hardening results from a kind of internal “damage” to the metal as it is forced into a new shape. Here’s how it happens: Hammer-blows knock individual atoms out of place. Rows of atoms, forced to slide over other rows, don’t always resume their ideal arrangements in their new locations. Instead they pile up in tangled dislocations. These defects act like walls and boulders. They harden the metal by resisting further deformation. If then annealed, the heat gives the atoms enough energy to shake themselves back into proper arrangement. But if not annealed, the metal stays harder. With enough damage, the piece of metal breaks. (For an easy demonstration, crush a piece of aluminum foil into a ball. Then flatten it out again. Repeat. Within a few cycles the foil will tear. Its malleability has been destroyed through work-hardening.)
Work-hardening could be a metaphor for human experience. We’ve all known bad times when life seems to be beating us down. In Hebrew one word for such troubles is “tzarah.” And the form of something, its shape, is “tzurah,” from the same word-root. In my daily prayers, I thank G-d for the conditions and experiences, tzarki, of my life, which give shape to my personality. Hopefully the tzarot of life result in a beautiful form, a wise and compassionate human being. But, unless annealed in the fire of trust, of belief that “this, too, is for the good,” tzurah can make a person hard, filled with a sense of internal damage.
Secrets of a “stretchy” metal
Unlike aluminum, gold can be bent, pounded, and stretched to a fraction of the thickness of a human hair, and still not break. Does gold work-harden at all? Yes it does. Under the hammer, gold atoms get pushed out of their proper arrangements like any other metal atoms. How, then, to account for gold’s exceptional malleability and ductility?
The cause lies right on the metal’s surface. It’s tarnish—or rather, gold’s lack of tarnish.
Tarnish is the brown or black film on fine silver that begs for a jar of silver polish. Tarnish has several relatives with various names and dispositions: the pleasant green patina that covers old copper, the destructive red rust that eats through iron, the invisible clear coating on aluminum. They are all chemical compounds formed by the metal reacting with the atmosphere. Gold, however, does not tarnish, rust or form a patina. The reason why will be explored, with G-d’s help, in another post. Here, we’ll examine the connection between tarnish and malleability.[7]
As the metal is squeezed thinner and thinner, its surface area grows. Metal atoms at the surface pull their electrons out of the “sea,” to bond instead with nearby atoms of oxygen or with atmospheric pollutants such as sulfur. These bonds have tightly defined lengths and directions. Therefore, the compounds making up tarnish are brittle, as explained above.
A defect in the arrangement of metal atoms behaves something like an air bubble trapped between two smooth layers of plastic. You can move the bubble by pushing on the plastic nearby. If the edge of the plastic is open, you can push the bubble out from under the plastic. The bubble disappears. But if the edge is sealed, the bubble gets trapped there.
A tarnished surface acts like a sealed edge. As the metal is worked, dislocations and other defects are pushed along below the surface. They become trapped there and pile up. Eventually the metal structure becomes so full of defects that it breaks.
But since gold doesn’t develop a layer of tarnish, defects of work-hardening can move unhindered to the surface.
As Betzalel made the first menorah he would have used both annealing and deliberate work-hardening. Forming the basic shape would require occasional annealing to keep the gold malleable. But once finished, with all the ornamental cups, knobs and flowers G-d called for, hammer-taps over the entire surface would harden it. Was this enough to make the menorah proof against dents and scratches? Possibly.
And they were made…
All questions about the menorah’s manufacture could be answered if only we had the original to examine. Unfortunately, we don’t have it. Nor do we have any of the ten menorahs of pure gold that King Solomon made for the Temple that he built.[8] When Nebuzaradan’s army conquered the ancient Jewish kingdom,[9] those menorahs were taken to Babylon as spoils of war. Although the Jews returned to the Holy Land less than one hundred years later, the Bible does not mention the menorahs any further.
Arch of Titus © Can Stock Photo v0v
Similarly, the menorah made for the Second Temple became a victim of war. The Arch of Titus depicts it being carried in boastful procession through the streets of Rome. That menorah vanished in 455 CE, when Vandals conquered Rome. According to rumor, it’s hidden in the basement of the Vatican. The Vatican denies this.
Throughout history’s millennia, the menorah continues to represent Jewish identity. Its image appears, painted or carved or inlaid as mosaic on synagogue walls, on tombs, and even as decorations on household objects. Its shape suggests a tree—a universal symbol of life. Its function was to give light, symbolic of wisdom, joy and all that is good and holy. Not surprising, then, the menorah is the official symbol of the new-born Jewish state of Israel. The menorah of Israel’s official state emblem is shaped like that on the Arch of Titus. Its message is clearly ironic: Titus’s Roman Empire is gone, but Israel’s people are still here.
In rebuilt Jerusalem, across from the Knesset (Israel’s Parliament) stands a 4.3-meter (fourteen feet) tall
The Knesset Menorah
By de, CC BY-SA 2.0
bronze monument shaped like a menorah. Carvings cover its surface depicting events of Jewish history. Meanwhile, devout Jews continue to pray for the prophesied era of genuine, world-wide peace. At that time the Moshiach, descended from King David, will build the Third Temple. A new Menorah will stand within it, to share its light with the entire world.
[1] Exodus 25:31-40
[2] Midrash Tanhumah 2, Parshat Shimini 10.
[3] Rashi, commentary on Exodus 25:31.
[4] Author’s calculation based on data from https://hypertextbook.com/facts/1999/BrianLey.shtml and The Physics Factbook, An encyclopedia of scientific essays, viewed September 17, 2018.
[5] Rashi, commentary on Exodus 25:39.
[6] Electrons don’t actually move from one end of a piece of metal to the other. That’s because they are randomly knocked around as they bump into metal atoms which are, themselves, rapidly vibrating. However, if electrical “pressure” (voltage) is applied across the metal piece, the overall drift of electrons will be from one end to the other, somewhat like the motion of a line of dominoes. Individual dominoes (electrons) don’t move far, but the motion itself (the current) quickly spans the entire line.
[7] Nutting, J. and Nuttall, J. L. Gold Bulletin (1977) 10:2.
[8] First Kings 7:49.
[9] Jeremiah 52:19