This is a story about love, writes Erin McClam … About inscrutable complexity and remarkable simplicity, about the promise of forever. It is about obsession and devotion, and grand gestures and 4,000-word love letters.

It is about a curious group of people with an almost religious zeal for a mind-numbing string of numbers. Actually one number, made up of a chain that is known — so far — to be more than one trillion digits long. They are the acolytes of the church of pi.

And once a year many of them gather to talk about pi, rhapsodize about it, eat pi-themed foods (actual pie, sure, but so much more), have pi recitation contests and, just maybe, feel a little less sheepish about their unusual passion.

That day falls on Wednesday this year: March 14. Or 3.14. Obviously.

It also happens to be Einstein’s birthday.