What put them on the road to art collecting?

The proverbial bolt of lightning launched Minneapolis art collectors Sam and Patricia McCullough on a love affair with the American folk portraits that they've lent to the Minneapolis Institute of Arts.

"We didn't have that much on the walls of our house then, and what we had wasn't very exciting," said Sam recently, recalling a morning stroll down New York City's Madison Avenue in 1974. "The Whitney Museum had up a show called 'The Flowering of American Folk Art.' So we walked in and saw it, and were so excited we could hardly eat our lunch that day.

"What appealed to me was that it was so abstract, it was almost leaping out of the canvas," he continued. "It complemented our American furniture and it was nonacademic."

Soon they were visiting New York galleries, consulting museum curators and bidding aggressively at auctions in obscure New England towns. As their collection grew, they became expert on everything from 18th-century hand-mixed pigments to the impact of photography, whose invention in the 1840s ruined the era's portrait market.

"We prefer our portraits to be a little bit pretty, like Catharina, who is very pretty," said Patricia, pointing to Ammi Phillips' 1825 "Portrait of Catharina van Keuren," a porcelain-cheeked beauty who is the show's signature image. One of the more famous of American folk artists, Phillips is a highly sought-after talent.

A Phillips painting recently sold for $450,000, Sam said, "but it was not nearly as pretty as Catharina."

"You can be interested in art from many angles," said Mary Olson who, with her husband, Doug, has lent four 19th-century landscapes, a fruit still life and a flower study to the show.

Inspired by a trip through the Hudson River Valley led by an institute curator, the Olsons began collecting 19th-century American landscapes from that region.

"I just like woodland interiors," Mary said, discussing an 1860s Asher B. Durand vista of sheep grazing on a rocky outcrop overlooking a wooded valley with misty mountains in the distance. When they bought the painting at auction, a layer of varnish somewhat obscured the sheep and the lovely blue background. Once the painting was cleaned, those features confirmed their instincts about the picture's quality.

A seascape by William Trost Richards launched the couple into a spirited discussion of the artist's biography and debate about which year, 1865 or 1866, he summered on Nantucket and most likely did their picture of waves rolling toward a sandy bluff topped by more tiny sheep.

No, the Olsons don't have a sheep fetish. Cows and sheep appear often in 19th-century landscapes simply because they naturally would have been roaming about the countryside in that era.

"This is a real gem because it has such a sense of spontaneity and freshness about it," said Mary of the Richards painting.