Dan Leeson is a person with many interests and multiple professions. For 30 years he was a successful IBM business executive with a career in computing. At the time of his retirement in 1987, he was responsible for the world-wide market planning activities for large-scale disk storage devices. Leeson is an authority on the history of computing and is published in the periodical "Annals of the History of Computing," a journal of the American Federation of Information Processing Societies. For 25 years, he was an active national lecturer for the Association of Computing Machinery. His 1962 book on computer programming is one of the earliest in the industry.
Simultaneously during these same years, Leeson also functioned both as a professional performing musician and as one of the world's leading Mozart scholars. He has authored many articles dealing with the Austrian composer and is co-editor of the volume of the complete Mozart edition that contains the bulk of Mozart's wind music. Leeson is published in the Mozart Jahrbuch, Music & Letters, The Instrumentalist, The Musical Times, Musical America, MadAminA, the International Journal of Musicology, and many other musical publications, both scholarly and general. He is author of more than 50 musicological articles. In addition, he has written program notes for the London Proms concerts, the San Francisco Symphony, San Francisco's Midsummer Mozart Festival, and others. For his writings he was awarded the 1992 Artist Fellowship for Writers of Creative Nonfiction by both the California Arts Council and the Arts Council of Santa Clara County, California. In February 1991, Leeson was an invited speaker at the Salzburg Mozarteum as part of the International Congress of Mozart scholars commemorating the bicentennial of the composer's death. Leeson was musicological consultant to both Ohio State University's Mozart Festival in May 1991, and the Columbia River Mozart Festival a month later. In July 1991, he was a guest lecturer and performer at the Chatauqua Institute in Chatauqua, New York. In January 1992, he was a keynote speaker for the Nevada Mozart Festival held in Reno and he concluded his bicentennial talks with a lecture to the California Mozart Society in Carmel/Monterey. In 1992 and 1993, he was a faculty member of the Mozart Opera Studies Institute sponsored by San Francisco State University and California State University, Fresno. In the summer of 1995, he was guest lecturer and performer at Alaska's Anchorage Festival. For two years he devoted himself to research on the subject of the the Mozart Requiem and was invited to speak of his work at the Millenium Festival commemorating 1,000 years of Austrian history. He is still an active contributor to the musicological journals and has had technical papers published in both the International Journal of Musicology (1998) and the Mozart Jahrbuch (1997, 1998, and 1999). Most recently, he gave the 2000 John Warner Wilson Memorial Lecture at the twenty-seventh annual conference of the Research Council on Mathematics Learning and was invited to speak on the subject of "Mozart and Mathematics" at seven American universities. His topic asserts that Mozart may have had a latent talent in mathematics and that this unknown intellect guided the development of some of his compositions.
Leeson is no longer an active performer but before his retirement he had been bass clarinetist with the San Jose Symphony orchestra for 20 years. He has also performed with a number of other prominent orchestras such as the New Jersey Symphony, San Francisco Opera, San Diego Symphony, Oakland Symphony, Midsummer Mozart (San Francisco), the Mozart Orchestra of San Luis Obispo and many others. He was also bass clarinetist with the New Sousa Band.
In his retirement, Leeson has undertaken yet a third career which takes advantage of his advanced degrees in mathematics. He now teaches that subject at De Anza College in Cupertino, California. Leeson developed and taught the only two-year college class on the History of Mathematics given in the United States. He does private historical research and enjoys visiting cemeteries because of his genealogic interests. His fiction is also now being published and he is writing a book of autobiographical short stories. Leeson is married to the former Rosanne Dryfuss and is the father of two children.