If your time machine got jammed in the past, what would you need to rebuild all of modern civilization? Mango sits down with Ryan North, author of the new book How to Invent Everything, to talk about how to make soap, why leeches were pretty useful for a very short period, how to invent a better horse harness, and why windmills just might be superior to waterwheels. Oh, and how to understand all of Western religion and philosophy through high-fives.