If jam bands all played slow jams, and if slow jams were all potent moral philosophy, then many of us would be down at the water's edge worshiping Maze, featuring Frankie Beverly. Instead Maze remains essentially unfamous. It is the wise tortoise of late-'70s black-pop groups, lasting without celebrity, horn arrangements or crossover radio hits. Of those groups -- the Commodores, Funkadelic, the Gap Band, the Ohio Players and Earth, Wind and Fire -- only Maze, based in Northern California since 1972, remains consistently prized as a live band, still reasonably intact with its singer-songwriter, Beverly, and two of its original members, the percussionists and singers Roame Lowry and McKinley Williams. Maze hasn't made an album in 16 years. But that's all right. It exists as a shared experience. This month it was the closing act of the Essence Music Festival in New Orleans, a spot it has held for 15 straight years. After a short break it came to the Beacon Theater on Friday. The band's shows are rehearsed rituals, working up to a rare and special audience feeling: deep, sentient serenity, not the usual kind of lose-yourself pop catharsis. It's done by repetitive funk in slow to medium tempos, without a lot of instrumental flexing; moderation is everywhere. Maze's songs aren't marathons, but five or six minutes long. One of its two keyboardists, Carl Wheeler and Vance Taylor, is often holding a steady tone as backdrop, while the bassist Larry Kimpel and the drummer Chris Johnson make the rhythm pop. The songs slow the heart rate, establish hypnosis and spread altruism. They don't take you to the other side of consciousness, or make you forget where you parked. But that's all right. The guitarist, Jubu, could handle much more than he does -- he's got the long-form improviser's inner glow -- but his solo on 'Golden Time of Day' felt perfect: about two minutes, building up to short licks spaced apart by six beats of rest. During each rest he wiped his left hand on his pants, and the crowd screamed at the casualness of the gesture. You come away from a Maze show with a prolonged light buzz, a clear adult self-awareness; you're excited not by virtuosic variations but the return of the theme. On Friday Beverly sang about love and trust, wandering a circle at center stage, gesticulating with his arms just a little bit in his white clothes and cap, never seeming egomaniacal or needy. His voice was half-scorched, and some of the usual traces of Donny Hathaway and Sam Cooke weren't coming through. But he managed by keeping it in the middle register and by adding small vocal gestures to the rhythm cycles -- percussive uh-uhs and dibba-dibbas, gospel grunts. His lyrics are about joy and desire, but he works realism, as well as a horror of hurting anyone, into his euphoria. In 'The Morning After,' from the band's 1993 album, 'Back to Basics,' he sang: I know what you're feeling; I have been there before. How will we know what we're doing, and what if we both should want more? I know it looks like it's real But afterwards how will you feel Will you feel bad, will we both feel sad? I want to know this right now. Responsibility funk: the gift of the 1970s. And in 'Joy and Pain,' which has been the band's live centerpiece for years, always with disco-ball lights spinning throughout the house, he sang about the duality of all experience, counseling, 'There will be sorrow, but you will endure.' Slow and steady wins the race. 