When I was nine, the treehouse I "helped" my dad build in the backyard became the Apollo-mission lunar module. I modified it to be even more "real."

If I close my eyes and go back to those feelings, a thrill creeps up from my toes to the tips of my ears.

I would not as a child have described my feelings about my spaceship treehouse as magical. An important part of me knew we would never use it to fly to the moon or anywhere. But another important part of me did not care. I was thrilled to be able to play as if it were real.

My parents seemed bemused that I took it all so seriously. Fortunately, they didn't press it, leaving me free not to break the magical spell that made my play so exciting and enriching.

To this day, I can look at illustrations of the old Apollo spacecraft and name most of the important parts. And that tree house is no small part of why I studied engineering later in life. But even after I learned how to calculate orbits and ballistics, I never managed to recapture the full magic that enchanted me as a child.