Increasingly it was the mystery and the intellectual challenge of understanding prehistoric civilizations rather than the simple amassing of artifacts that sparked Lilly's imagination and energy. The transition was revealed in his changing relationship with W. A. McGuire, a colorful Missouri dealer in Indian relics. At first Lilly and McGuire poked fun at the silly pretensions of professional archaeologists. McGuire's interests were in the artifact itself and the price he could obtain for it, not in the human cultural pattern it might reveal. Their relationship warmed to the point that Lilly proposed a joint digging expedition. But then in February, 1932, Lilly wrote McGuire: "For better or for worse, I have cast in my lot with the scientific archaeologists and, as a result of that, I have stopped buying from all sources, and particularly those [like McGuire] from which I am unable to obtain the exact descriptions of the locations and manner of the excavation, with all details." Politely but firmly he concluded his relationship with the Missourian by saying "you stand on the other side of the fence."

This maturing outlook between 1929 and 1932 occurred in part because Lilly discovered others in Indiana with serious interests in archaeology. The prehistoric past had long attracted Hoosiers. The scientists of New Harmony, particularly Charles A. Lesueur, had undertaken archaeological investigations in the 1820s. And nineteenth century Hoosiers shared the fascination of Americans with the myth of the mound builders-the romantic notion that some vanished race of superior people had constructed the large earthen mounds of the Ohio Valley. Nineteenth-century archaeology had no serious institutional base in Indiana, however. There were no museums or university programs. Not until the mid-1920s did a push toward organized, careful excavation, collecting, and study begin, directed by the Indiana Historical Society and the Indiana Historical Bureau. The former was a private institution, organized in 1830, the latter a state agency. Both were headed after 1924 by Christopher B. Coleman, a Ph.D. trained historian, a skilled administrator, and a most likeable gentleman. In 1926 Coleman organized the first modern dig in Indiana, at Albee Mound in Sullivan County. The same year he formed an archaeology section of the Indiana Historical Society. The Society soon would become the major sponsor of archaeology in the state. Among the archaeology section's most active members were E. Y. (Dick) Guernsey, a state legislator from Bedford who had first interested Lilly in the subject, William Ross Teel, an Indianapolis stockbroker and the archaeology section chairman, and Glenn A. Black, a cost estimator for an Indianapolis company that produced industrial scales. All were amateurs, but their interests were serious.

By late 1930 Lilly was part of this group. In December he attended an Indiana Historical Society lecture given by Warren King Moorehead. Moorehead had directed one of the first major digs in the state, near the Wabash River in Posey County in 1898. At the time of his Indianapolis lecture he was director of the Robert S. Peabody Foundation for Archaeology in Andover, Massachusetts, and one of the most widely known of North American archaeologists. Moorehead greatly impressed Lilly and his associates, and they soon invited him to return for a serious tour of the state's archaeological sites. On May 6, 1931, Lilly joined Moorehead, Guernsey, and Black for a three-day trip through southern Indiana, to Martinsville, Worthington, Merom, Vincennes, New Harmony, Angel Mounds, and Boonville. In search of archaeological sites, Lilly tramped fields and woods alive with an Indiana springtime, talked with local collectors, and enjoyed the company of Moorehead, Guernsey, and Black. He ended the trip fully stuck to the prehistoric past. "The memory of the three delightful days in your expedition," Lilly wrote Moorehead, "will always be a happy one."

Summer, 1931, brought an intensity for archaeology that Lilly had shown previously only for the pharmaceutical business. This he would do for the next two decades, he spent much of his vacation at Wawasee in pursuit of the prehistoric past. He located what he hoped was an Indian burial at Cedar Point on Lake Wawasee. He planned its excavation and concentrated on "learning surveying for the purpose of helping make this expedition a real scientific attainment " Not until the fall was he able to undertake the Cedar Point dig. It was "more or less a disappointment," he concluded, for he found no skeletal remains. It was his first and last such dig.

Lilly's interests were not those of a "dirt" archaeologist, although he always enjoyed visiting sites and studying excavations. Rather, his major interest and talent developed in the library and the study. By early 1931 he owned several shelves full of archaeology books, and at Wawasee that summer he spent every morning reading, "trying to learn something about Indiana archaeological data by working up county bibliographies." Lilly worked hard to prepare this bibliography and decided eventually to submit it to the Indiana Historical Bureau for publication. It was his first such effort. He learned the trials and tribulations of publication when Nellie Armstrong, the Bureau's meticulous editor, forced him to do two revisions. The Bureau published his "Bibliography on Indiana Archaeology" in 1932.

In addition to work on the Cedar Point dig and the bibliography, Lilly also began in the summer of 1931 to contemplate the larger questions in American archaeology. In particular, he focused his attention on the question of time and the challenge of categorizing, dating, and arranging in chronological sequence the several cultures of prehistoric peoples who had lived in Indiana before the Europeans arrived. When he read of the recent success of A. E. Douglas in dating the Pueblo ruins of the American Southwest by studying tree rings in their wooden timbers, he wrote Moorehead: "I am all fired up with the possibility of finding a log in some of these mounds and burials, from the rings of which we might figure the age of some of these places like Douglas did in the Southwest." Lilly's interest in time, in developing a chronological synthesis and taxonomy of prehistoric cultures in Indiana, would become the driving challenge throughout his life of archaeology.

To answer the questions of time, Lilly knew, required extensive excavations of sites and the intellectual power of professional archaeologists. In 1931 he put a new man to work in the field. Glenn Black would contribute more to Indiana archaeology than any other person. He would also become Eli Lilly's closest friend.

Black was born in Indianapolis in 1900, fifteen years after Lilly. By the late 1920s he was actively collecting Indian artifacts and reading relevant books and articles. In 1931 the Depression brought a reduction and eventually an end to his work with Fairbanks, Morse and Company. When offered the chance to serve as guide and driver for the Moorehead expedition in May, 1931, Black eagerly accepted. Moorehead and Lilly were much impressed with the young, earnest, and unemployed Black. They concurred that he should be set to work in Indiana archaeology. Lilly agreed to pay his field expenses and a salary of $225 a month. Black began work in mid-June, 1931, preparing a map of sites in the state. While Lilly was reading archaeology at Wawasee, Black worked on the project in Lilly's Sunset Lane library and in his third floor collections. By midsummer Black was in the field, digging in Greene County and sending frequent, detailed descriptions of his finds to Lilly. He and Lilly also began to correspond more broadly about archaeology. Lilly wrote Black of Douglas's tree-ring dating and advised him that if he unearthed any logs to "guard them as you would your life."

Lilly took a risk in employing Black, particularly because he had no formal training in archaeology and only a high school education. Doubtless Black's earnestness, capacity for hard work, and determined interest in archaeology impressed Lilly. But Lilly recognized also the need for more formal education. So did Indiana Historical Society head Coleman and archaeology section chairman Teel. They knew that Fay-Cooper Cole at the University of Chicago had recently begun to train firstrate archaeologists. Professor Cole was pressuring the Society to hire one of his Chicago students. Coleman and Teel supported Lilly's preference for Black, but the three men agreed that the young Hoosier needed more academic polish. They wished, Lilly wrote Moorehead, to avoid the scorn of one Dr. Cole in case he would say, 'Black, Black, who is this man Black,?' So Mr. Teel is trying to make arrangements to get in some more scholastic education, probably this winter, so we can at least say he has been trained under Shetrone, or 'so-and-so.' This Black is willing to do and I still have hopes of making a good man out of him. He surely has the diligence and enthusiasm, which is a large part of the picture.

From October, 1931, through May, 1932, Black studied with H. C. Shetrone at the Ohio State Museum. Shetrone was the author of a book on the mound builders. He and the institution he headed were widely respected in archaeological circles. He had been reluctant at first to take on Black, advising Teel that the Society ought instead "to bring in a first-class scientifically trained man." But Black eventually won over Shetrone, who later wrote Lilly that "we should be glad indeed to have him as a member of the Museum staff." In l935 Black had the pleasure of considering and rejecting a formal offer to join the Ohio State Museum staff.

Lilly closely watched Black's progress. He visited him in Columbus and corresponded frequently. He asked Black's help in recommending titles "to build up a good modern library on the subject of Middle Western archaeology" and to expand references for the bibliography he was preparing. Black responded fully to such calls, usually going beyond the specific request. The younger man remained a bit unsure of his relationship to his patron. Doubtless fearing disapproval, Black did not tell him of his marriage in late October, 1931, to Ida May Hazard. Ruth Lilly read the marriage license application in the Indianapolis newspaper, and Eli wrote immediately: "you are not springing a surprise on us, are you? Here is hoping." When Black confirmed the marriage and expressed his "hope that this step will meet with your approval," Lilly replied with "the heartiest congratulations to you and to Mrs. Black." The friendship between the two men would soon extend to a deep friendship between the two couples.

Black returned from Columbus in spring, 1932, in time for summer field work. Lilly continued to pay his salary, but now funneled it through the Indiana Historical Society so that "I can get credit on my income tax." By mid-1932 neither Black, Teel, nor Coleman made significant decisions relating to the Society's archaeological work without first consulting Lilly. His checkbook was always open for Black: "When it comes time for me to put any money into the Historical Society for the digging purposes, let me know and I shall send a check promptly." Lilly's commanding role was formalized and expanded in 1933 when he agreed to serve as president of the Society, a position he held until 1947. Black remained in the employ of the Indiana Historical Society until his death, his salary paid by Lilly. The patron always insisted that the Society "make no announcement or publication or use my name in connection with the proposition in any way."