Small earthenware lamps, made from double molds, were the most commonly used source of light during the Coptic period. A wick produced from plant fiber or linen fabric was placed in a reservoir filled with oil, generally castor or sesame oil, and illuminated. Religious symbols used as decoration, such as this variation of the Chi-Rho Christogram, the monogram for Christ 's name, were thought to offer protection for the lamp’s owner.
Julien Gréau, Paris; J. Pierpont Morgan, New York (by 1903–d. 1913; coll. cat., 1903, unpub., no. 288); his estate(1913–17; gifted to MMA)