Luca Pacioli was one of the greatest men of the Renaissance. He is also one of the least well known. This is surprising, for Luca Pacioli's manuscripts and ideas changed the way the world worked then, and continue to affect modern daily life.

Luca Pacioli was born in Sansepulcro, in Tuscany. He was probably born during 1445. His family was poor, and Pacioli's future seemed very unpromising. Pacioli joined a Franciscan monastery in Sansepulcro and became an apprentice to a local businessman. The young Pacioli had always loved mathematics though, and he soon abandoned his apprenticeship to work as a mathematics scholar.

Pacioli befriended the artist Piero della Francesca, one of the first and greatest writers and artists of perspective. Francesca and Pacioli journeyed over the Appenines, where Francesca gave Pacioli access to the library of Frederico, the Count of Urbino. The collection of four thousand books allowed Pacioli to further his knowledge of mathematics.

Francesca also introduced Pacioli to Leon Baptist Alberti, who would become Pacioli's new mentor. Alberti brought Pacioli to Venice and arranged for him to tutor the three sons of the rich merchant Antonio de Reimpose. During this time, in the year 1470, Pacioli wrote his first manuscript at the age of twenty-five. The book was about algebra and was dedicated to the Reimpose boys.

Alberti also introduced Pacioli to Pope Paul II. Paul encouraged Pacioli to become a monk and dedicate his life to God. After Alberti died in 1472, Pacioli took the pope's suggestion, and took the vows of Franciscan Minor.

In 1475, Pacioli became a teacher at the University of Perugia, where he stayed for six years. He was the first lecturer to hold a chair in math at the University. In his lectures, Pacioli stressed the importance of putting theory to practical use. This emphasis on application of theory made him unique among his peers. While at the University of Perugia, Pacioli wrote his second manuscript, dedicated to the "Youth of Perugia."

After 1481, Pacioli wandered throughout Italy, and in some areas outside it, until he was called back to the University of Perugia by the Franciscans in 1486. By this time, Pacioli was beginning to call himself "Magister," meaning master, the equivalent of a full professorship in modern time.

The year 1494 is the only date during Pacioli's life that is absolutely certain. It was during this year that the forty-nine-year-old Pacioli published his famous book Summa de arithmetica, geometria, proportioni et proportionalita (The Collected Knowledge of Arithmetic, Geometry, Proportion and Proportionality). Pacioli wrote the Summa in an attempt to redress the poor state of mathematics teaching in his time. One section in the book made Pacioli famous. The section was Particularis de Computis et Scripturis, a treatise on accounting. De Scripturis was later described by some as "a catalyst that launched the past into the future."(Luca Pacioli: Unsung Hero of the Renaissance) Pacioli was the first person to describe double-entry accounting, also known as the Venetian method. This new system was state-of- the-art, and revolutionized economy and business. The Summa made Pacioli a celebrity and insured him a place in history, as "The Father of Accounting." The Summa was the most widely read mathematical work in all of Italy, and became one of the first books published on the Gutenberg press.

Pacioli's important manuscript made him instantly famous, and he was invited to Milan to teach mathematics at the Court of Duke Lodovico Maria Sforzo in Milan. One of his pupils would be Leonardo da Vinci. During the seven years Pacioli and da Vinci spent together, the two would help each other create two masterpieces that would withstand the test of time. Da Vinci illustrated Pacioli's next and second most important manuscript De Divina Proportione ("Of Divine Proportions"). Pacioli taught da Vinci perspective and proportionality. This knowledge allowed da Vinci to create one of his greatest masterpieces, a mural on the north wall of the Santa Maria de Gracia Dominican cloister. This mural is the most famous painting of the fifteenth century, known as "The Last Supper." The geometry Pacioli taught to da Vinci would occur in many of da Vinci's later works. Da Vinci mentions Pacioli many times in his notes.

In the years that followed Pacioli's relationship with da Vinci, he continued to teach and write. In 1509, De Divina Proportione and a work on Euclid were published in Venice. In the same year, Pacioli gave an important lecture on "Proportion and Proportionality," a lecture that emphasized the relationship of proportion to religion, medicine, law, architecture, grammar, printing, sculpture, music and all the liberal arts.

In 1510, Pacioli was appointed director of the Franciscan monastery in Sansepulcro, much to the dismay of his fellow monks. In 1514, Pope Leo III called Pacioli to the papacy in Rome to become a teacher there. Scholars are unsure about what happened to Pacioli afterwards, but they are fairly certain that he never made it to Rome. Pacioli probably died on June 19, 1517 in the monastery in Sansepulcro.