Rory Gilbert performs in Rock of Ages at the Cygnet Theatre.

“Hanging on the promises in songs of yesterday,” the verse goes, “I know what it means / To walk along the lonely street of dreams.”

"Lonely street of dreams" is hardly great poetry, and it’s barely good songwriting. But it perfectly fits the song, “Here I Go Again,” which became a big hit for 1980s hair band Whitesnake. Eventually. Perhaps it was ahead of its time when first released, along with a music video, in 1982. Or maybe the music was the problem. Whatever the trouble, when the band released a newly recorded version of the tune in 1987, only one of the original musicians was involved: backing lead singer David Coverdale. The rest of the band had been fired, and the new radio-mix featured an entirely new roster of musicians. But the song was finally a sensation, and Coverdale’s appearance in a new music video with his future bride (model Tawny Kitaen) briefly made the glam rocker a star.

The song, and Coverdale’s story of perseverance, also perfectly encapsulates the musical Rock of Ages, which plays at the Cygnet Theatre until August 25. The play weaves a loose, mostly comedic narrative around “the promises in songs of yesterday,” primarily the hair metal hits and power ballads that provided a soundtrack for the very decadent and self-indulgent Los Angeles scene of the mid- to late-80s. Twenty years on, the nostalgia in these tunes is self-evident, and through the gauzy filter of time, they no longer feel quite as embarrassing a part of our cultural history.

That generation of rockers was performing a pastiche of their 1970s icons and role models — Led Zeppelin, Black Sabbath, and the like — who had become as famous for sex, drugs, and hotel-room destroying antics as they had for their music. Long hair, tight leather pants, and hard partying became as vital a part of the rock star pantomime as shredding guitar solos. Each band was a daft but pretty collection of skinny, tattooed boys engaged in nihilistic performance, with the pursuit of one's dreams at any cost as the closest thing any of them had to an ethos.

Those dreams were shallow in the extreme: mainly, they involved becoming famous rock stars, living on tour buses, drinking bottles of whiskey, and passing out next to long-legged models. Which dovetailed nicely with the dreams in the heads of busloads of young people moving to Los Angeles. To this day, Hollywood’s most celebrated ideal is the pursuit of fame. First-time Oscar winners invariably pepper their acceptance speeches with tales of their early struggles or denigrating jobs, and include some variant of “Follow your dreams!” or “Dreams really do come true!”

The question then becomes: is the unwavering pursuit of your dreams made valid only once you achieve them? If you wind up, as so many fame-seeking Los Angeles transplants have, living a pleasant suburban existence in the San Fernando Valley, have you failed because your dreams failed to come true? Is the only true path to believe in yourself and strive for public success, even if it means revamping the same song again and again until it strikes gold?

Ask Coverdale, who has continued to sing, even as he’s many times since disbanded, reassembled, then disbanded and reassembled Whitesnake. “Here I go again on my own / Goin’ down the only road I’ve ever known / Like a drifter, I was born to walk alone / and I’ve made up my mind / I ain’t wasting no more time.”