Philip Johnson once said that a great architect might see one in 10 of his designs built. At a lecture on Thursday, two years to the day after his last speech at Yale, Frank Gehry chose to focus on the unbuilt nine.

“Last time I was here, I showed everything I’d done since my bar mitzvah,” Gehry quipped to a standing-room-only crowd at the Yale University Art Gallery on Thursday. “But what never got built is interesting, too.”

Interesting not least because there is so much. In a Friday interview with the News, Gehry, considered by many to be one of the world’s foremost architects, discussed the challenges facing architects and the buildings he has nevertheless completed.

“Architecture is a precarious profession,” he said Friday. “The approval process hamstrings you, the political process hamstrings you, the finances hamstring you. It’s a miracle if you get something built.”

Miracles, then, have been pretty common for Gehry. From his Guggenheim Museum in Bilbao, Spain, to the Walt Disney Concert Hall in Los Angeles and even the Yale Psychiatric Institute in New Haven, the 79-year-old architect has been nothing short of prolific.

And, supporters say, he has been nothing short of brilliant. Gehry does not necessarily like such words, though; indeed, he said he views buildings more in terms of their context than their cachet.

“The best you can hope for,” Gehry said, “is that each new building thinks of the buildings around it as a good neighbor and creates real relationships.”

Gehry’s Disney Concert Hall has been hailed precisely for that cohesion. The building’s sail-like steel façade relates famously to the adjacent Dorothy Chandler Pavilion — and, in a sense, to all of Los Angeles.

But nobody has asked Gehry to design another concert hall.

“When I did Bilbao in 1997, I didn’t get another museum,” he said. “I did the concert hall four or five years ago, and I didn’t get another one.”

That could have something to do with one of Gehry’s favorite topics: denial.

Take chain-link fencing — a material that Gehry has elevated from merely industrial to perhaps beautiful — as an example. The fencing is made in vast quantities; Gehry once spent an hour at a factory and watched four workers, in just those 60 minutes, produce enough of the interlocked metal to cover 15 miles of the Santa Monica Freeway.

“Now if you speak to people, they’ll tell you they hate chain link,” Gehry said. “But look at how much everyone’s buying. That’s denial.”

More worrisome for Gehry — who, for better or worse, almost always attracts attention — is the tendency of skeptics in various cities to dismiss his work as soon as his name is brought up.

“Cities are filled with bad buildings and nobody complains,” he said. “But if I do a building, there’s all sorts of protests.”

Such opposition has presented hurdles for Gehry’s work — including the plan for the massive Atlantic Yards development in Brooklyn that he first presented some five years ago and that has since changed dramatically.

“I’m supposedly doing 20 or 30 buildings in Brooklyn, but at this point I doubt if it’ll ever all happen,” Gehry acknowledged on Friday.

If there are hurdles to Gehry’s work elsewhere, Yale must present relatively few. Teaching this semester as the Eero Saarinen Visting Professor at the School of Architecture, Gehry has taught and spoken regularly at Yale — something he has done since 1979.

In his studio class last week, the professor worked with students on their proposals for the transformation of Lincoln Center in New York. It is a project with special significance for Gehry, who had at one point considered making designs for the ongoing renovation of the site.

But if that project is among the unbuilt nine for Gehry the architect, it is very real for Gehry the teacher and his students.

“I’ve heard the same concert in my Disney Hall and at Lincoln Center and it’s just not the same,” Gehry said. “It’s a loaded problem, but I think the kids are finding good solutions.”

And that may be why teaching is so exciting for Gehry. Even the most informal discussions with students bring him in touch with the newest generation of architects.

“I see hope in my students,” Gehry said. “There’s a sense of adventure, an openness to ideas, that is really special.”

“I’ve got three favorite things,” he said. “Food, sex and Yale.”