What do you need a magnifying glass for? To make fire?
That's a good use for it, yeah. It comes in handy in some 1st aid applications, too. You can use it to cook small pieces of meat on a raft if sushi doesn't float your boat, it makes kind of a handy drill, if you're feelin' really hard core, you can cauterize wounds with it. If you suspend it over head it'll keep some flying insects out of your hair. They're pretty handy.
....ok.. you to..lol
