You sigh and look back to your work, picking up the half-completed coil and starting to unkink the wire. “Some smart guys at NASA – remind me to explain that group to you sometime, you might get a kick out of it – said there are three categories of knowledge. You have your known knowns, your known unknowns, and your unknown unknowns. I’ve found this very useful advice for engineering.” You finish your work straightening the wire, and resume winding it by hand. “Obviously, you have your pool of knowledge. Then there’s everything you’re aware you lack, the gaps in your knowledge, all the things you might need help to understand. Know what I’m saying? But after that there’s everything else. All the knowledge that you have no frame of reference for, that you can’t even know you don’t know.” You’ve found a rhythm with the coiling now. It’s a lot easier to slip into now that you’re not exhausted. “In the end, it’s the unknown unknowns that get you. I need to watch out for them. Even you need to watch out for them.”