How many letters do you handwrite and mail in a year? If you're like most people, the answer is probably zero. Email, texting, and social media have essentially rendered the practice of writing letters by hand obsolete. Despite their being old school, a person might still write one when they want to add a personal touch that doesn't carry over digitally  -- say, a child writing to his pen pal, a foreign exchange student reaching out to family from the other side of the world, or a hopeless romantic who wishes to spill his guts via pen and paper. Can you guess how many letters Thomas Jefferson, the third president of the United States, wrote in his lifetime? Mind you, there was no Yahoo, Facebook, or Twitter in the 1700s and 1800s. Even the telephone wasn't invented until 1876, and Jefferson died in 1826. That means people in Jefferson's time had to make do with communicating through correspondence. And, evidently, Jefferson was nothing short of a pro. He...