ON (city) ŏn (אֹ֖ן, אֹֽון; pillar-city), capital of the thirteenth nome of Lower Egypt, about six m. NE of Cairo and three m. N of modern Heliopolis.

Biblical references. Joseph married Asenath, daughter of Potiphera, priest of On, which is tr. Heliopolis by the LXX (Gen 41:45, 50; Isa 45:20). The LXX includes On as one of the cities in Egypt built by the Israelites (Exod 1:11). Isaiah 19:18 may mean that there will be Jews worshiping the Lord and talking Heb. in the City of the Sun (RSV), i.e. Heliopolis (some Heb. MSS including IQ עִ֣יר הַהֶ֔רֶס; other Heb. MSS עִ֣יר הַחֶ֔רֶס, “city of destruction” KJV). In the 2nd cent. b.c. there were Jews and a Jewish temple in Leontopolis, eleven m. N of Heliopolis (Jos. War, VII. x. 2-4; Antiq. XIII. iii. 1-3). Jeremiah 43:13 predicts that Nebuchadrezzar will break the obelisks of Heliopolis (בֵּ֣ית שֶׁ֔מֶשׁ; KJV “Beth Shemesh”). Obelisks originally at Heliopolis have been taken to Rome and Istanbul and two to Alexandria, and then one of these two to London and one to New York. Only one remains at On. Ezekiel 30:17 warns of the death in battle of the young men of On (MT אָ֛וֶן, “wickedness,” KJV “Aven,” but the LXX and Vul. imply אֹ֥ון, followed by RSV).

Religious and intellectual center. From the earliest times On was a center for the worship of the sun-god. The walls (now below ground) of the great temple area measure about 540 ft. by 1,375 ft., and within these walls were temples of the sun at Atum, Ra-Harakhte, and Hathor. Sacred to the sun was the bnbn stone, a small, primitive obelisk; a sacred išd tree; and the crested heron, called phoenix by the Greeks (Herodotus II. 73). The bull-god Mnevis also was worshiped at On, and his sacred pillar, the iwn, gave the city its name. The priests of Heliopolis were reputed to be the most learned in Egypt (Herodotus II.3) They studied astronomy and philosophy, and the Gr. philosophers Plato and Eudexus are said to have learned from them (Strabo XVII. 1. 29). The chief priest had the title “Greatest of Seers,” the office and title which Joseph’s father-in-law prob. held.

Visit of the Holy Family. According to the medieval Arabic Gospel of the Infancy, 24, the Holy Family, in their flight to Egypt (Matt 2:14, 15), visited al-Maṭariyah, which occupies part of the site of On, and took shelter under a sycamore tree. A sycamore there, traditionally identified with this tree, recently died at the age of about 300 years, and both Christians and Muslims still revere its gnarled trunk.

Bibliography W. M. F. Petrie, Heliopolis, Kafr Ammar, and Shurafa (1915); B. Porter and R. L. B. Moss, Topographical Bibliography of Ancient Egyptian Hieroglyphic Texts, Reliefs and Painting, IV (1934); A. H. Gardiner, Ancient Egyptian Onomastica, II (1947); H. Bonnet, “On,” Reallexikon der ägyptischen Religionsgeschichte (1952), 543-545; A. Rowe, “The Famous Solar-City of On,” PEQ, XCIV (1962), 133-142; O. F. A. Meinardus, In the Steps of the Holy Family from Bethlehem to Upper Egypt (1963).