The belief that others can turn around is why Farmer has volunteered for four years at the Camden Residential Community Home.
Each Tuesday, he mentors a group in this rehabilitation program for nonviolent juvenile offenders who are headed back to the community.
At 65, he's old enough to be their grandfather, "but I identify with them," says Farmer, a compact man with a penetrating gaze.
"I understand exactly how they feel - when they wake up in the morning in jail, what it's like if they don't have a visitor, what it's like to have to fight for respect."
The deeply religious father of two, who lives in the city's Fairview section with his wife, Janice, has worked as a hairstylist since the mid-1970s, when he completed a term in state prison for armed robbery.
All told, his multiple incarcerations represent "a dozen precious young years . . . wasted," he writes in The Turnaround (Windsor Press and Publishing), his vivid account of life behind, and beyond, prison walls.
Farmer is one of a half-dozen volunteers who provide counseling and other services to the young men at the residential facility that stands behind chain-link fences at Sixth and Atlantic in South Camden.
"Juvenile offenders have a great deal of respect for people they believe are authentic," Superintendent Furquan Sharif says. "Gerald is authentic. He has credibility. He has an impact."
I can't help but wonder how that's possible, given the age difference and the skepticism of youth.
But Larry Miles, whose La Unique African American Bookstore in downtown Camden sells The Turnaround, says Farmer's life story "can help young people on the streets today."
The world outside has changed since Farmer went to the juvenile facility in Jamesburg, N.J., in 1960, but "it's still the same jungle" inside, the author notes.
It doesn't look like that at Camden Residential Community Home, where hallways gleam and the atmosphere seems more academic than penal.
The 13 residents, ages 16 to 19, are not free to leave, however. And if they don't change how they think, Farmer warns, they may never enjoy lasting freedom.
Enter his "wisdom seeds" - basically, Bible verses he asks the boys to memorize as substitutes for criminal ways of thinking. "The seeds grow," Farmer says. "And they bring forth positive fruit."
He quizzes them on the concept of "reaping what you sow." He passes out worksheets and offers a rap version of his poem about "stumbling blind."
Listen quietly, don't make a sound
'cause some young thug on his way down
might hear this truth
and turn his life around
The eight serious faces around the table suggest that Farmer is someone the teenagers respect.
He knows something deeply personal about virtually all of them: That they've stood before a sentencing judge as their loved ones cried.
"Like mine did," he says.
After the prayer circle, Farmer and I chat outside. A car glides along Atlantic Avenue, leaving behind a trail of bellowing beats.
"I feel really uplifted because we had a good session tonight," Farmer says.
"Working with these guys makes my life feel meaningful" - he pauses and looks down, then finds the words - "to where it's worth living."
Contact staff writer Kevin Riordan at 856-779-3845, firstname.lastname@example.org, or @inqkriordan on Twitter. Read the metro columnists' blog, "Blinq," at http://www.philly.com/blinq.