Exhibits
Digging for Meaning: Rocks, Gems and the Yale Seal

The Yale University seal with its well-known Latin Lux et Veritas — “light and truth” — banner has been in regular use since 1736. The Hebrew phrase Urim V’Thummim across the center of the seal has origins that stretch back thousands of years to ancient rocks, minerals and gems in the time of Moses.

The Breastplate of Judgement

 

The priest above is wearing the breastplate of Judgement.

Frontispiece of the Vestitus
Sacerdotum Hebraeorum,
from Johann Braun, Amsterdam, 1680.

 

According to the Book of Exodus, the Urim and Thummim were kept in an interior fold or compartment of the Breastplate of Judgement worn by the High Priest of the ancient Israelites. The Breastplate was used to reveal divine answers to important questions facing the entire community, such as whether or not to go to war.

First worn by the High Priest Aaron, the Breastplate was set with 12 precious stones, each with the name of one of the 12 tribes of Israel engraved on it. However, the exact nature of the Urim and Thummim remains a mystery.

Divine Lights?

 

One widely held interpretation is that the Urim and Thummim provided divine light for the 12 precious stones, illuminating specific engraved letters to spell out an answer to the High Priest. Modern biblical and archaeological scholarship, however, suggests a somewhat different interpretation. After considerable research, Yale Professor Emeritus W.W. Hallo concluded that the Urim and Thummim were rocks of some kind, or even dice, that were used to obtain divine guidance.

Divine Lights?

 

Breastplate unfolded.
From Johann Braun, Vestitus
Sacerdotum Hebraeorum,
Amsterdam, 1680.

 

Scholars have suggested that the Urim were light-colored rocks, probably alabaster, and that the Thummim were dark-colored ones, probably made mostly of hematite. The High Priest would pose a question and then draw lots by pulling out Urim and Thummim from the Breastplate. The answer to the question would be given by color. For example, the light-colored Urim could have meant “no” and the dark Thummim “yes.”

For the divine answer to be considered definitive, it is thought that the process had to be repeated several times, and the same color rock had to be pulled out each time. Urim can be translated as “lights” or “lamps,” whereas Thummim is translated to mean “perfect,” “truth, “integrity,” or “honesty.” So, “Lights and Honesty” or “Lights and Truth” are acceptable translations of the Hebrew phrase on the Yale seal, and match the Latin Lux et Veritas, as the designers of the seal must have known.

Divine Lights?

 

Ephod with the Breastplate
folded and attached.
From Johann Braun, Vestitus
Sacerdotum Hebraeorum,
Amsterdam, 1680.

 

Scholars have suggested that the Urim were light-colored rocks, probably alabaster, and that the Thummim were dark-colored ones, probably made mostly of hematite. The High Priest would pose a question and then draw lots by pulling out Urim and Thummim from the Breastplate. The answer to the question would be given by color. For example, the light-colored Urim could have meant “no” and the dark Thummim “yes.”

For the divine answer to be considered definitive, it is thought that the process had to be repeated several times, and the same color rock had to be pulled out each time. Urim can be translated as “lights” or “lamps,” whereas Thummim is translated to mean “perfect,” “truth, “integrity,” or “honesty.” So, “Lights and Honesty” or “Lights and Truth” are acceptable translations of the Hebrew phrase on the Yale seal, and match the Latin Lux et Veritas, as the designers of the seal must have known.

Twelve Precious Stones

 

Gold, from California.

 

The precise identities of many of the 12 precious stones on the Breastplate are still debated, although there is reasonable agreement on their colors. Here we present examples of some of the rocks, minerals and gems that may have been used, along with alabaster, hematite and gold. These specimens are all from the extensive mineral collection at the Yale Peabody Museum, which itself dates back to the early 19th century.

Rocks, Minerals and Gems

 

“Lapis lazuli,” the ornamental
form of lazurite, from Afghanistan.

 

A mineral is a naturally occurring crystalline solid with chemical and physical properties that vary within defined limits. Most minerals form by inorganic processes like the cooling and crystallization of lava; such processes do not involve living things. New minerals are always growing—in caves and volcanoes, at the surface and deep within the Earth. More than 3,500 different mineral varieties are known today.

Rocks are naturally formed, consolidated masses of minerals. Some of the precious stones on the Breastplate, like jasper and lapis lazuli, are rocks since they are composed of many individual mineral crystals.

Gems are minerals or other natural substances that have been cut and polished, and are valued for their rarity and inherent beauty.

Rocks, Minerals and Gems

 

Left: Corundum, variety ruby, from Viet Nam.
Center: Yellow corundum, from Sri Lanka.
Right: Corundum, variety sapphire, from Burma.

 

The beautiful colors of minerals are usually due to their chemical composition. Chemical impurities can become incorporated into a crystal as it grows. Light traveling through the mineral interacts with the impurities in the crystal structure, ultimately giving rise to the colors we see.

Some minerals have a characteristic color; for example, lazurite is nearly always blue. Others, such as corundum, come in a variety of hues (red rubies, blue sapphires) depending on the chemical composition of the mineral. Increasingly, rocks and minerals are being artificially colored using chemical or heat treatments; for instance, bright blue agates are artificially made and would never form naturally.

Beryl, variety emerald, from Colombia.

 

Exhibition Curator
Jay J. Ague
Professor of Geology and Geophysics
Yale Peabody Museum Curator of Mineralogy

References
Exodus (28:15–30, 39:8–14), Leviticus (8:8)
Hallo, W.W., 1966. Akkadian Apocalypses. Israel Exploration Journal 16:231–242.
Hallo, W.W. and W.K. Simpson, 1998. The Ancient Near East (2nd ed.). Fort Worth: Harcourt Brace College Publishers, 324 pp.
Horowitz, W., and V. Hurowitz, 1992. Urim and Thummim in light of a psephomancy ritual from Assur (LKA 137). Journal of the Ancient Near Eastern Society 21:95–115.
Kunz, G.F., 1971. The Curious Lore of Precious Stones. New York: Dover, 406 pp.
Oren, D.A., 1985. Joining the Club. New Haven: Yale University Press, 440 pp.

Illustration reference
Braun, J., 1680, Vestitus Sacerdotum Hebraeorum. Amsterdam.


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