Here's What Leonardo da Vinci's To-Do List Looked Like in 1490

Even the brilliant mind of Leonardo da Vinci needed to jot things down in a notebook so he could remember what he needed to do. The only difference, of course, is that da Vinci's to-do list was much more complex than ours. I mean, who needs to calculate the measurement of Milan and its suburbs and learn how to repair… » 11/21/11 4:00pm 11/21/11 4:00pm