vade mecum —noun something a person carries about for frequent or regular use. a book for ready reference; manual; handbook. Luggage sets come with some large bags and at least one small one to be used as a carry-on. We naturally divide things for a journey. Which items will we need handy? Which are relegated to checked luggage? Understanding our vade mecum can provide insight into what is most important to us. And, what we’re most dependent on. Things we think we can’t live without. Sure, it includes the obvious…wallet, phone, house keys. What else? When you’re packing for a trip, what makes it under the seat in front of you? Is there a…