Prince's Purple Rain put the Minneapolis Sound on the map

Forty years ago this weekend, the music world "purified itself in the waters of Lake Minnetonka ."

Why it matters: The theatrical premiere of the film "Purple Rain" on July 27, 1984, catapulted Prince to superstardom and introduced his Minneapolis Sound to a worldwide audience.

What they're saying: At the time of its release, Prince "was a critical darling and had a very devoted underground fan base, a Black fan base," Andrea Swensson, the Minneapolis music journalist who hosts the artist's official podcast , told the NPR show "1A."

• "It really was 'Purple Rain' that took him from an underground art rock darling to an absolute supernova."

The intrigue: The film propelled the album — released one month earlier — to the top of the Billboard charts and set up Prince's North American tour that fall.

Zoom in: "Purple Rain" was also a love letter to Minnesota, letting First Avenue , the fall colors in the Minnesota River valley , and the IDS Center's Crystal Court glimmer on the silver screen.

• The film featured other Minneapolis Sound talents like Prince's former bandmate Morris Day , co-star Apollonia Kotero , and the film's quiet heroes Wendy Melvoin and Lisa Coleman .

Kyle's thought bubble: Let's face it, the script was a mess — though there were gems. ( "Say the password, onionhead!" )

• I was also surprised at how dynamic Prince was onscreen even when he was not singing. I shouldn't have been. The man was a treasure.