Mailing a Metaphor

This mailing from the National Parks Conservation Association doesn’t look too different from the outside. The white, glossy outer consists of two 6-inch-by-9-inch panels folded together and tab sealed. The face panel is bare save the address box and NPCA return address, while the back displays a four-color thumbnail picture of a cliff and the teaser, “When you think of our national parks, what words come to mind?”