If you are like me, you've probably seen them, but you didn't know what they were. You've seen them on cereal boxes and campaign buttons, store displays and CD covers. My earliest recollection is a button from the 1960 presidential campaign. Tilt it one way, you see Richard Nixon; tilt it the other way, you get Henry Cabot Lodge.

This seems like an insignificant advertising gimmick, but it really involves a quite complicated and intricate technology. They are called "lenticular" images. Our five clergy were on a retreat recently, and at a Burger King we saw a poster advertising the latest gimmick for children, which even used the word "lenticular." But five fairly intelligent, master's degree-holding, theologically-trained clergy—even including one Episcopalian—had no idea what the word m…