The atmosphere on Capitol Hill's brick sidewalks stays frosty year round as the power-walking professionals rush along in suits of wool-blend armor, their earphones in place, smartphones loaded and eyes focused dead ahead.

But things changed at the corner of Second Street and Massachusetts Avenue NE. That's where streams of pedestrians converge near Union Station, the U.S. Senate office buildings, the Federal Judiciary Center, the Heritage Foundation and other buildings packed with prestige and power.

For the past decade, this was where the late Peter Bis kept his office, sitting on a blue plastic crate under an oak tree, sharing cigarettes, coffee and conspiracy theories with whoever passed by, greeting most of them by name. He was the friendly homeless man with his own website, business cards and a life story that -- even when warped by schizophrenia -- touched thousands.

"Hey professor! Happy Easter," he shouted a few years ago. I nodded and returned the greeting.

A few paces later, Bis hailed me again. "Wait a minute," he said. "Orthodox Easter isn't 'til next week this year, right?"

He was right, of course. Had I shared that personal detail with him or did he glean that tidbit of liturgical minutia from one of the newspapers he read, day after day? Anyone who knew him could describe similar mysterious encounters.

That’s precisely what people have been doing lately at St. Joseph's Catholic Church, a block from that oak tree. The parish held a memorial Mass for Bis last week, a month after he died of a heart attack at age 61. Worshippers entering the quiet sanctuary passed a copy of a painting of Bis called "The Contemplation of Justice."

Over the years, many people offered advice about how he could get off the street and put his savant-like memory to good use, said Deacon Gary Bockweg, who delivered the homily. At one point, Bockweg suggested that he work as a Wal-Mart greeter, but Bis said he was over-qualified for that job.

Bis often said he had a doctorate and once taught at a university. Was that true? After all, he also volunteered memories about a romance with Princess Diana, his years working as a spy, clashes with Vatican leaders and his origins as an extraterrestrial. There was lots of evidence that he really had worked in a shipyard in Oregon.

In his own way, Bis truly was a teacher, stressed Bockweg.

"He taught us that everyone we walk past deserves to be recognized as a real person, even if their appearance is deceiving," said the deacon, in his sermon. "If Pete had sat in silence, looking down at the sidewalk, or if he'd called for our attention with less friendly, less charming words, we would probably never have gotten to know the Pete inside there. ...

"We've been walking past his vacant spot under the tree for a few weeks now ... each day growing a little more accustomed to the emptiness there, and that unheard greeting. Over the years we had come to take Pete's presence for granted. And now, we're reminded that we're all just passing through this life."

When Bis first visited St. Joseph's, he was neatly dressed and well groomed. He took Communion in Mass and seemed in control of his life, although he remained quiet.

Things were different when he returned months later, limping and "using an empty wheel chair for a walker," said Bockweg. "Then the wheelchair started to fill up with bags and books. And then suitcases piled on top of that. ... He also grew more talkative, and we got to know him."

His friends remember him fondly, but with a touch of guilt. It's hard to know how to help the homeless, especially those fierce in their resolve to go their own way.

That was Peter Bis.

Yet something also drove him to reach out, to accept some gifts and offer others the gift of his memory and attention, said parishioner Joe Jones, who sang the Irish lament "Danny Boy" at the end of the Mass in honor of his friend.

"Peter Bis was a gentle soul. ... There was certainly much more there than a grunt and a curse word," said Jones. "The last thing people do today when talking to a stranger is call them by name. That's how Pete connected. ... He called us by name and that slowed us down. That made Pete real to us."