Luca Pacioli knew a thing or two about keeping the records straight. He was a Franciscan friar and mathematician who lived during the Italian Renaissance (he was, in fact, a friend of Leonardo da Vinci), and he is called the "father of accounting" because he was the first to publish a detailed description of bookkeeping practices that are still used today. Among his other counsel, Pacioli advised merchants to keep an accurate ledger with debits entered on the left side and credits on the right. The word per contra calls to mind this time-honored practice of balancing items on one side of a ledger against those on the other. The term comes from Italian, and it translates literally as "by the opposite side (of the ledger)."