A “good accountant” is one of the three essentials of business, wrote Luca Pacioli in the 15th century in his book, Summa de Arithmetica, a first edition of which just sold at Christie’s in New York for $1,215,000. In the book, Pacioli lays out the foundation for modern business and writes that the other two essentials are “cash or credit” and “good internal control.” The book also gives the first description of double-entry bookkeeping, which, of course, led to the proliferation of green columnar pads that cluttered every accountant’s office. For those of you who lost out on the bidding, you can get a reprint on Amazon for $43.54.