Barbara Liskov (Turing Award Winner): "Python has modules, but it doesn't have encapsulation. It allows code on the outside to muck around with what's going on on the inside of a module. Encapsulation is a crucial part of making modularity work. And when you're building big programs so you have many programmers working on them, your team is really only as strong as your weakest programmer. So it's nice if the compiler can enforce things and make certain kinds of bad behavior not possible."