Urschel, the former Baltimore Ravens guard and current MIT math Ph.D student, on his book “Mind and Matter: A life in math and football,” on why he left football at 26 for an academic life, and why he thinks a balanced life is the best life for him.Branch, the Pulitzer Prize-winning New York Time sports writer, on his book “The Last Cowboys: A pioneer family in the new West,” on the challenge of a ranching family making in the back country of Utah, on his imaginative writing style ... and a discussion on how a great writer also needs to be an excellent reporter as well.