If Jonathan Richman didn't already exist, we would never have thought to invent him, which is a testament to his originality and to the shortcomings of our collective imagination.

For more than 35 years, Richman has been a tireless advocate of hopeful romanticism, rugged individualism, and unyielding optimism, traveling the world like some postmodern Jimmy Stewart with a guitar, telling anyone who would listen that, despite all the hard-bitten cynicism that surrounds him, it's still a wonderful life.

He is, in short, the immaculate heart on the dirty sleeve of rock-and-roll - which, in part, explains why the Farrelly Brothers used his musical interludes as a palate cleanser between the bodily function jokes in 1998's There's Something About Mary.

Performing before a capacity crowd Tuesday night at the First Unitarian Church, Richman was in peak form. Bearded and dressed in a green button-down shirt with a crisp white T-shirt peeking out from underneath, Richman had the crowd eating out of his hands - clapping in time, singing along, even joining him on stage to dance - all of which, he insisted, would make the evening "more like a party than one of them concerts."

That Richman can disarm and charm a crowded, darkened church basement with little more than an acoustic guitar and the shuffling beats of longtime drummer Tommy Larkins is a testament to his prodigious powers as a song-and-dance man and to the infectiousness of his worldview.

Even strong medicine like "When We Refuse to Suffer," which rails against the modern inclination to numb ourselves chemically against negative emotions and insists that feeling bad is better than feeling nothing at all, tasted like a spoonful of sugar.

Richman gently mocked the pretentiousness of youth with "My Affected Accent" and "Bohemia" and celebrated the magic of adult love in "Hurricane When She Came" and "My Baby Love Love Loves Me."

He turned each song into a long, elliptical vamp, punctuated with witty asides, herky-jerky dance moves, and snake-charmer guitar. At one point, he cartwheeled across the stage, much to the audience's delight.

While he mostly focused on newer material - such as the pining "O Moon Queen of the Night on Earth," the let's-get-physical "These Bodies That Came to Cavort," and the Old Master homage of "No One Was Like Vermeer" - Richman did dig deep into his back catalog, most notably for "Old World" from Jonathan Richman & The Modern Lovers, arguably one of the most auspicious debuts in the history of auspicious debuts. He encored with "I Was Dancing at the Lesbian Bar," which was as mirth-making as the title suggests.

Years from now - many years, we hope - when his epitaph is written, it will say something along the lines of "He left the world a happier place than he found it."