The Christian Science Church, which a century ago was America’s fastest growing church, is rooted in the idea that prayer can conquer the most pernicious of ailments. But even at the Christian Science Church, some problems require a different sort of intervention.

The First Church of Christ, Scientist sits majestically on some of downtown Boston’s most coveted real estate. Inside the 3,000-seat triple-domed sanctuary, known as the Mother Church, is its loved and pampered baby, the world’s largest Aeolian-Skinner pipe organ.

Waves of silver and gold pipes shooting 50 feet up spread across the front of the sanctuary, but most of the organ’s 13,483 pipes are concealed behind them. They’re controlled from the organ’s elaborate console, the keyboards and panels of knobs – called stops – at the foot of the pulpit. Every pipe has a unique timbre and pitch, and the tiniest fluctuation in temperature or humidity can alter its sound.

Most pipe organs are tuned once or twice a year, and kept in churches heated only when used. The Mother Church is kept at a constant 70 degrees, and its organ is tuned every few weeks.

“It truly is one of the most magnificent organs of the world,” says Bryan Ashley, the church organist.

Tuning is normally done by two professional organ technicians, one sitting at the console, and the other, up in the rafters, making minute adjustments to the pipes.

But the week before Christmas, Ashley was bothered by one particular pipe – and the tuners were booked solid.

Ashley demonstrated the problem. “As you can hear, it’s a little bit flat. This is in tune, this is out of tune.” Sometimes, Ashley can work around a problematic pipe or wait for the tuners to come back. But he wanted to use this pipe – a bright reed stop used for trumpet tunes, accompanying hymns and large ensembles – in the Christmas service.

So he wedged a pencil to hold down the bothersome key, puts on ear-protectors and headed up ladders to the chambers where the pipes reside.

If you died and went to pipe heaven, this is what it would look like: multiple levels dense with orderly rows of precisely-engineered graduated pipes, as far as the eye can see. Cylinders and cones of tin and wood, zinc and copper. Small as pinky fingernails, massive as telephone poles. Don’t go up if you’re scared of heights, or can’t walk a straight line on a narrow lip of wood. And don’t dally up there, because your body heat will alter the pitches on other pipes.

Once Ashley located the offending pipe, he gently tapped the tuning wire attached to it until the pitch rose the littlest bit. Then, watching his step, he returned to the console for the moment of truth.

“That was scary,” he admitted.

Testing the pipe against others, Ashley sighed with relief. “It sounds good. Sounds lovely,” he said. “Now we can have Christmas.”

No doubt, Ashley believes that God is in the details.