When invited to present colloquia talks, I usually talk about atomic clocks and I am sometimes asked what a theorist is doing in this highly experimental field. I was thinking about this question for a while and then I was on a plane browsing through an in-flight catalog (you know the one that advertises stuff that you may want but really do not need) and I realized how to answer this question.
There was an ad for a beautiful wristwatch accompanied by a story on the fine craft of clockmaking. The story was comparing making a wristwatch to building a skyscraper out of matchsticks. So I thought, by that account, experimentalists working on atomic clocks are performing miracles. And if these experimentalists are walking on water, my role as a theorist is to show them where the stepping stones are.