Have you ever sat around a bonfire with friends late into the night? Every once in a while someone adds an extra log or pokes the pile with a stick to keep the blaze alive, but inevitably there comes a point when it’s time to let the fire die. The flames slowly shrink until there’s nothing left but the red glow of embers, and your fingers and toes quickly begin to feel the difference. If you stay out for too long, even the blanket you’re wrapped in won’t do you much good.