Before I took up reporting, I spent a lot of time thinking about what goes on in the unsourceable confines of our individual brains.

For a generation of psychologists, neuroscientists and philosophers of mind, one man had more influence on our understanding of the human mind than anyone else. And most of us never knew his name.

H.M. died yesterday, and the initials with which the scientific community respectfully - and affectionately - maintained his privacy are no longer required. they might stay in use for a while, though. Patient H.M. was a research subject for over fifty years, and old nicknames can be hard to shake.

H.M.'s amnesia was the opposite of the amnesia in daytime soaps. He knew the name the textbooks always concealed. He could tell stories and ask after people from the life he lived before the experimental brain surgery he underwent as a young man. After that surgery, for the rest of his 82 years, he never formed a memory of another event. He could carry on a conversation until you left the room; if you came back in, he had no idea you'd ever met. It's like that folk trivia about goldfish, only in a person, not a fish.

What's amazing, though, is that though he didn't remember events or names, he did remember. He recognized the patterns, voices and feelings of his post-surgery life, he just never knew where he recognized them from. I've heard his experience compared to a permanent state of déjà vu.

He must have known the spaces around M.I.T. where he lived out his life like the back of his hand. He must have learned, without knowing when he learned it, to accept acting on knowledge he couldn't explain.

In one study he solved the same puzzle repeatedly over subsequent days. He found the solution faster every day until he had the steps memorized. But he still approached each attempt unsure if he'd be able to figure it out.

Studying H.M. was a career-long commitment. He knew which researchers he liked and which he didn't, and would confidently state made-up histories explaining how he knew the people he considered his friends. Those scientists must be experiencing a unique and complicated feeling of loss.

There have been other cases of amnesia like H.M.'s, but it's usually brought about by alcoholism or an infection that visits indiscriminate damage around the brain. H.M. was removed from the stream of time with a surgeon's scalpel - personality and crossword puzzle fondness intact.

The Times' obit is here. This is good if you like your history of science from primary sources. If you're really intrigued you can put this book on your list. The next few days will surely produce some thoughtful eulogies from the people who think hardest about thought.

Memory research - and, by definition, H.M. - haven't been part of my life for years. Reminded of him now, there's something comforting in his bittersweet story. We all do the most amazing things without knowing what's going on.

Hyat Tarnikov likes to spend his afternoons in the Arslanbob teahouse talking to the foreign visitors. The teahouse extends over the narrow, rumbling rapids of a mountain stream, and the other patrons are all elderly men with long white beards, tall, embroidered felt hats and long coats. They remove their scuffed and muddy outer boots to expose soft leather shoes before pulling their legs onto the teahouse’s carpeted divans. The crowd changes very little from day to day.

Arslanbob is a home to 12,000 people, high in the mountains of southern Kyrgyzstan. There’s no cell phone reception, and everyone shares the one satellite phone in Hyat’s house. In Soviet days it was a popular resort, but now the economy relies on the surrounding walnut forests. When the harvest is bad, Hyat says, the long mountain winter is particularly bitter and sometimes people starve.