Scaling a mountain is a popular metaphor for overcoming a great challenge. Well-meaning friends have compared our family’s fight against Batten disease to scaling a mountain.

But on a clear day, you can see the top of a mountain. And thousands of people have reached the summit of Mount Everest, the world’s highest peak at over 29,000 feet. If I had the desire to climb Everest (I don’t), someone could tell me how to do it. Even Edmund Hillary, who made the first known successful ascent, had Tenzing Norgay, a Nepali sherpa climber, to guide him to the roof of the world.

Fighting Batten disease isn’t like climbing a mountain. It’s like traveling to the center of the earth.

No one can tell us which way to go. No one has been there. Though my sister is far from the only person with Batten disease, she, like all others with a terminal illness, travels a path that is hers alone. We, like all those who love someone shackled by a monster like Batten disease, travel a path cloaked in shadows; a path for which there is no map; a path that had a hopeful beginning but no defined end.

The center of the earth is not a nice place to visit. Conditions are so excruciating that they can’t be replicated in a lab. The mantle is like a huge mountain range turned upside down, heated up and shaken, which causes constant avalanches. The outer core is molten iron. Deeper, the pressure is so intense that iron solidifies, even though the inner core is believed to be hotter than the surface of the sun.

As we hurdle downward on our journey – through cascading, rocky peaks, churning lava and broiling metal – we have to make lightning-quick adjustments. We have to change equipment. Sometimes, we don’t have the right equipment for the situation – but we have to forge on anyway. Some days, we suffer first-degree burns. Rarely do we suffer a wound that won’t heal. But in the center of the earth, permanent scars are facts of life.

The center of the earth is a dark place, and you never know what you’ll find around the bend. I fight this fight like it means life or death – because it does – and sometimes, I wonder, “When we get to the end, is it gonna be worth it? What’s at the end? Is the ending of OUR story the ending of THE story, for us?

Most journeys, like most decisions to scale a mountain, are chosen. We didn’t sign up for this trip. But we’re on it, and there’s no turning back.

Buried at the center of the earth is a giant crystal. If brought to the surface, it would stretch across more than half the continental United States.

Even the most hellish journeys have hidden wonders.