There are great moments of invention in any thinking person’s life. I don’t mean in the sense of inventing a product or system or anything like that, though that does happen on occasion. I’m talking about those moments of clarity when we realize something that we didn’t know before–something that a lot of other people might not yet know. It happens more often when we’re young and we have less experience and less information clogging up our brains, but it still can occur at any point in life, especially if you’re making an effort. It’s a positive, delightful experience.

But most learning–at least the really important lessons–isn’t delightful at all. It comes from pain and loss. The kind of shock or defeat that can recalibrate or even shatter a belief system. I’m talking mostly about emotional pain, though we learn, too, from the physical kind. And what becomes of people with a rare disorder that leaves them unable to feel physical pain? How does that affect their growth, their maturation? From a New York Times story by Justin Heckert about a teenager impervious to pain:

“When she was born, she didn’t cry. She barely made a noise, staring out from her swaddling with a blank red face. When she developed terrible diaper rash, so raw that it made Tara wince to even wash her, the pediatrician gave instructions to change her formula and put cream on the rash and keep it dry. ‘I kept thinking, But she’s not crying,’ Tara said. ‘The doctors dismissed it, but we’re thinking, What’s going on?’

When Ashlyn was 3 months old, the Blockers moved from Northern Virginia to Patterson, Ga., where Tara has family. At 6 months, Ashlyn’s left eye was swollen and bloodshot. The doctor suspected pink eye, but Ashlyn didn’t respond to the treatment, so they went to an ophthalmologist, who found a massive corneal abrasion. ‘And Ashlyn is just sitting there, happy as can be,’ Tara recalled. The ophthalmologist assumed she had no corneal sensation in her eyes, and referred them to the Nemours Children’s Clinic in Jacksonville, Fla. It took a while to get an appointment, and before they made it to Jacksonville, Ashlyn rubbed big red splotches on her nose and almost chewed off part of her tongue with her emerging teeth.

At the clinic, they drew Ashlyn’s blood and took scans of her brain and her spine, but the tests were inconclusive. Over the next 18 months, there were more tests. A nerve biopsy from the back of her leg left stitches that ripped when she was running. When the doctor finally gave his diagnosis, Tara was afraid she would forget the words, so she asked him to write them down. The doctor took out a business card and wrote on the back: ‘Congenital insensitivity to pain.'”