Catholic Encyclopedia (1913)/Lucas Pacioli
Mathematician, born at Borgo San Sepolco, Tuscany, toward the middle of the fifteenth century; died probably soon after 1509. Little is known concerning his life. He became a Franciscan friar and was successively professor of mathematics at Perugia, Rome, Naples, Pisa, and Venice. With Leonardo da Vinci, he was in Milan at the court of Louis the Moor, until the invasion of the French. The last years of his life were spent in Florence and Venice. His scientific writings, though poor in style, were the basis for the works of the sixteenth-century mathematicians, including Cardan and Tartaglia. In his first work, "Summa de Arithmetica, Geometria, Proportioni, et Proportionalita", Venice, 1494, he drew freely upon the writings of Leonardo da Pisa (Fibonacci) on the theory of numbers. Indeed he has thus preserved fragments of some of the lost works of that mathematician. The application of algebra to geometry, and the treatment, for the theory of probability also help to make this treatise noteworthy. The "Divina Proportioni" (Venice, 1509), was written with some co-operation on the part of Leonardo da Vinci. It is of interest chiefly for some theorems on the inscription of polyhedrons in polyhedrons and for the use of letters to indicate numerical quantities. His edition of Euclid was published in 1509 in Venice.
Paul H. Linehan.