You have to go back 4,000 years, colleagues said, to find someone as fluent in Sumerian as Miguel Civil. A Catalonian-born professor with a purported photographic memory, he spent decades studying ancient cuneiform tablets, examining the last wedge-shaped traces of what is probably the world’s oldest written language.

Dr. Civil, who was 92 when he died Jan. 13 at a hospital in Chicago, was a giant in the field of Sumerology, an expert in the Mesopotamian civilization that is widely credited with developing the first cities, sailboats, irrigation systems and potter’s wheels, as well as the seven-day week and writing itself.

“He was the most knowledgeable authority of Sumerian since 2000 B.C.,” said Christopher Woods, a fellow Sumerian scholar and director of the Oriental Institute at the University of Chicago, where Dr. Civil taught from 1963 until his retirement in 2001.

“There are hundreds of thousands of Sumerian tablets,” Woods added. “He had a complete mastery of these sources and a special genius at going beyond what the text said, making cultural connections that others were not able to do. . . . He was a master at getting into the heads of the ancients.”

As a written language, Sumerian originated around 3300 BC, according to Woods. By 1800 BC, around the time Hammurabi ruled over Babylon, it had largely become a literary language, akin to Latin in the Middle Ages. Then it was lost, forgotten until the 19th-century discovery of Sumerian cities and culture in present-day Iraq.

Dr. Civil participated in excavations at the ancient city of Nippur and assembled texts that resembled literary jigsaw puzzles, piecing together hundreds of clay fragments stored at institutions around the world. He also served on the editorial board of the Chicago Assyrian Dictionary, a monumental nine-decade work of scholarship that was completed in 2010 with the publication of its 21st volume.

“Civil was a brilliant linguist,” said Benjamin Foster, a Yale professor of Assyriology and Babylonian literature, “who carried forward the reconstruction of ancient Sumerian language and literature begun by Samuel Noah Kramer, Adam Falkenstein and Thorkild Jacobsen in the mid-20th century.”

Dr. Civil was especially renowned for his work on lexical lists, bilingual tablets that catalogued various terms in Sumerian and Akkadian, a Semitic language also spoken in ancient Mesopotamia.

“He took up many difficult problems, such as Sumerian phonology, grammar and semantics, and pioneered the use of computer technology to place small fragments of Sumerian writing in their original contexts,” Foster added. “We all stood in awe of his breadth and depth of knowledge and his originality of thought.”

The work was often exceedingly difficult; Sumerian is a linguistic isolate, a stand-alone language, like Basque or Etruscan. Scholars have spent weeks or longer trying to parse out the Sumerian distinction between terms such as “window” and “door.”

But Dr. Civil, colleagues said, seemed to have made his way through nearly every one of the tablets unearthed from Sumer, where scribes and other officials wrote down hymns, receipts, divorce records and the first known farmer’s almanac. Among the texts Dr. Civil examined was a 54-line poem expressing a homesick man’s love for his mother (“She is a lamb, good cream and sweet butter flow from her”) and a six-line tablet reading, “One who does not love the scribal art will not pay attention to Sumerian.”

In the 1960s, after a German scholar declared that a 19th-century BC Sumerian poem was incomprehensible, Dr. Civil promptly translated the piece — a hymn to Ninkasi, the Sumerian goddess of beer. The text was published in a scholarly journal and rediscovered 2½ decades later by Anchor Brewing president Fritz Maytag, who enlisted Dr. Civil’s help in replicating Sumerian suds.

The result resembled a modern cider and was “served in proper Sumerian fashion,” Maytag later said, “sipped from large jugs using long drinking straws fashioned to resemble the gold and lapis-lazuli straws found in the tomb of Lady Pu-abi at Ur.”

While Dr. Civil said he was pleased that the results “confirmed the overall correctness” of his translation, he resisted suggestions that Sumerians and other ancient peoples may have lived off beer. No, he told the Chicago Tribune, “they could hardly have laid the foundations of civilization if they were drunk all the time.”

Miquel Civil i Desveus was born in Sabadell, a center of the Catalonian textile industry north of Barcelona, on May 7, 1926. His father was a physician, and his mother was a schoolteacher. With a younger brother, he attended a Catholic boarding school at the Abbey of Montserrat, and he taught himself rudimentary Akkadian and Sumerian by studying the abbey’s vast collection of cuneiform tablets.

In 1955, he moved to Paris, where he unloaded trucks, painted houses, manned an elevator and hired extras at a film studio before taking a class with Jean Nougayrol. The French cuneiformist inspired him to study for a doctorate at the École Pratique des Hautes Études, where he mulled a career as a schoolteacher while deepening his knowledge of Sumerian script.

His decision to pursue Near Eastern studies was made after a meeting with Kramer, the longtime patriarch of Sumerian studies, who in 1958 invited Dr. Civil to join him at the University of Pennsylvania. He left for the Oriental Institute in 1963 — two years before he received his PhD from the École Pratique — and later said he had been mulling an offer from the University of California at Berkeley but settled on Chicago because it offered few distractions.

“There are not even any mountains to ski or climb,” he said, according to “The First Ninety Years” (2017), a scholarly essay collection published in celebration of his life and work.

Dr. Civil died of complications of a pulmonary infection, said his daughter Caterina Plummer. His marriage in 1960 to Isabel Martin Mansilla ended in divorce, but in recent years, they rekindled a friendship and lived together; at the hospital before his death, Dr. Civil referred to her as his wife.

In addition to Plummer, of Niles, Ill., survivors include a second daughter, Sofia Civil of Chicago; one brother; two sisters; four grandchildren; and a great-granddaughter.

Although Dr. Civil spent his career studying a long-dead language, he often noted its connection to the present and the opportunity it afforded to take a broader view of human existence.

“The recovery of the past represents a sheer enrichment of human thought,” he wrote in the foreword to “In the World of Sumer,” Kramer’s 1986 autobiography. “It is a sort of time travel in which, unlike in science fiction in which we encounter generally pitiful creations of an ethnocentric imagination in alien worlds, we make acquaintance with fellow humans who represent aspects of ourselves which temporal and cultural boundaries have made impossible to actualize.

“One day may come,” he continued, “when the study of man, frustrated by the limitations implied by the study of the present man with no possible knowledge of the long-range consequences of his behavior, will focus with new interest on man as a historical being, on the behavior of the species through extended periods of time. We will know then whether the belief in progressive changes in the quality of human life, paralleled by the technical progress of mankind, is based on a mirage or on facts.”