Steve Lopez thought maybe he would get a column out of the homeless man who was playing a violin with only two strings. He did get a column, and then more, and then a book, a friend, a lot of complications, an education, and a cause. The man he saw on the street was Nathaniel Ayers. The book is called The Soloist: A Lost Dream, an Unlikely Friendship, and the Redemptive Power of Music. And now the story of Lopez and Ayers is a movie starring Robert Downey, Jr. and Jamie Foxx.

I spoke to Lopez in a little coffee shop on Capitol Hill, just before his meeting with Hill staff to talk about mental health policy.

Why does our society do so poorly in helping people who are mentally ill?

There is a “There but for the grace of God” aspect to it, “This could have been me.” It is so easy to look past somebody, to wrap yourself in the generalizations and stereotypes — they might all be dangerous, they might all be capable of lashing out. But it is not a decision. These are our brothers, sisters, sons, daughters. As you go through this population you see that mental illness does not discriminate on the basis of race or income. It is cruel and unrelenting but people can be helped.

What do you hope to accomplish with this book and movie?

I want people to ask, “How does this exist in American society?” The mentally ill are shoved off into this human corral, out of sight, out of mind. Would we do this with cancer or muscular dystrophy? The answer is clearly no. The reason places like Skid Row exist is the stigma of mental illness. I hope this story shines a light on that and addresses some public policy issues.

Tell me about Nathaniel Ayers.

He was not typical but relatively normal. He grew up in Cleveland. A woman recently brought me a photo of him when he was very young, before the breakdown, just charming. You see the photo before the fall, there’s such hope in his eyes, a great future in front of him, passion for music, a great kid in a good family with a mother who had him mind his manners and go to piano class and get good grades, He gets whacked with this just as his career is about to take off. He was a former classmate of Yo Yo Ma.

How aware is he of his illness? Enough to help in his treatment?

Nathaniel has insight issues. There are times when he is very much aware of his own condition and times when he is not. In some ways he has it made. He found out his purpose in life and has everything he needs.

What have you learned from him?

I found him on the street and wanted to help him get him out of his situation. My life was hectic and frantic. He forced me to reconsider the definitions of success and happiness. In some ways this is a story about a man who has lost everything but has a purpose in life that those of us who are considered successful would envy. A change comes over him when he is with the music. He is more coherent and sane. It could be the science and math of it — he sees and hears things we don’t and it is hard to process all the signals, but the notes are in the same place they have been for 200 years. The world can be so terrifying for people who have schizophrenia. So you build a cocoon, a tin foil hat, or something. In Nathaniel’s case he will do his scrawlings. In that safe cocoon of his, music is the medicine, it is what keeps him whole.

I don’t think “What a wonderful life,” I just think most people do not have his purpose, joy, and passion. For me, journalism had become such a negative experience because we sit around newsrooms grousing about the good old days. Seeing Nathaniel made me realize I do not want to spend the last days of my career grousing about what used to be. I heard about an opening in California for a media person for mental health services, thought about doing that, and then decided I could find my purpose by continuing to write. I realize I’m working on the story of my life. It is not only the human drama but he’s helping me and giving me a chance to shine a light on our public policy failures. I am a storyteller, and that is my passion, equal to Nathaniel’s. It would be foolish to give it up. There are other ways to tell stories, and this new movie is one of them. So now I still write but I savor it a little bit more knowing it is what I chose to do. Nathaniel has made me feel much more grateful and devoted.

What were your disappointments or frustrations? In the book you talk about how you felt when he lashed out at you.

I felt very conflicted when despite my best efforts the condition was more powerful, bigger, more relentless than I was. It wasn’t Nathaniel, it was the condition. But how much patience do you have? I understand how families throw their hands up. You ask, “Can I sacrifice all this time for no guarantee of making a difference?” I know and admire and love him too much to turn back. Recovery is not linear, you slide a lot. Nathaniel has been in an apartment for three years. He has a girlfriend, he comes to concerts. Before, he didn’t consider himself worthy enough to see a concert. He would say, “People should not have to sit next to me.” But he now goes himself sometimes. That growth in him is pretty remarkable. Partly it is a friend handing him a lifeline, partly his own courage.

What is it people most misunderstand about mental illness?

They think, “We offered help and they didn’t want it” or “They can go to a shelter.” They do not realize how many challenges and psychological hurdles mentally ill people face. They have a fear of rules, a fear of having to be more social, a fear of being ostracized. Nathaniel feared a return to the world in which he had snapped. All of the places he played on the street were really noisy. He said, “The city is my orchestra.” With the noise, it was impossible for him to hear his mistakes. He did not want to leave the place he used to play because he said the statue of Beethoven would be alone. We got him a bust of Beethoven for his apartment so he could still keep Beethoven company.

What kind of recommendations are you on Capitol Hill to talk about today?

One of my heroes and mentors, Sister Mary Scullion, co-founded Project Home in Philadelphia. They have taken over abandoned neighborhoods and rehabbed the houses. They have turned lost neighborhoods into anchors of the community. We have Project 50, survey teams with clipboards find the 50 neediest and most desperate and chronically ill people and give them wraparound services, coordinating health care, housing, everything. One year into it, 88 percent are still in housing. It is a double tragedy. People are on the streets and we know what works and can bring them in. Not only is this the humane thing to do, it is the cost-effectrive thing to do.