[Gil Troy is professor of history at McGill University and the author of ''Morning in America: How Ronald Reagan Invented the 1980s."]

THE MFA'S exhibit ''Speed, Style, and Beauty: Cars from the Ralph Lauren Collection" is ridiculous, excessive, and fun, indulging everyone's inner shopper. ''The cars are equally as unattainable as any Gaugin, but we imagine owning them," MFA curator Darcy Kuronen told an interviewer, equating great art and flashy sports cars as just more toys to crave. Yet this shameless exhibit of exhibitionism, celebrating Ralph Lauren values in a Brahmin bastion, does what museums have always done. It holds up a mirror to us collectively, demonstrating who we are and who we wish to be, for better and worse.

For centuries, the tug of war between virtue and materialism, has shaped America -- and Boston in particular. In the classic 1958 biography of John Winthrop, historian Edmund Morgan defined ''The Puritan Dilemma" as ''the question of what responsibility a righteous man owes to society." Ronald Reagan, who in the 1980s reminded his fellow citizens of Winthrop's vision of their country as a ''shining city upon a hill," may be the modern American most responsible for resurrecting that dilemma.

Reagan mixed paeans to prosperity with old-fashioned values talk. His easygoing individualist nationalism encouraged idealism while excusing materialism. Reagan was fortunate to preside over a great economic expansion, when the students of the '60s began earning serious money, trading in their tied-dyed T-shirts and dashikis for Ralph Lauren suits and sweaters. By the 1980s, few worried about the basics of food, shelter, or clothing. Many acquired new insecurities about their rations being nutritious or nouvelle enough, their homes being well-decorated or big enough, and their outfits being flattering or fashionable enough. Many frittered away time and money managing these new insecurities of abundance, as others preyed on these worries and profited.

Ralph Lauren was one such missionary of Reagan's new materialism. He and Calvin Klein would become household names wrapping Americans in fabrics and fragrances that seemed to convey status and shape individual identities. Lauren epitomized and exploited the aspiring middle-class kids' desire to find acceptance in the upper echelons of America's theoretically class-free society....

With crowds flocking to salivate over Ralph Lauren's Bentley, Bugatti, Porsche, and Ferrari, it is clear that the '80s sensibility still reigns. With dowagers bemoaning the blurring of the lines between high culture and low culture, with intellectuals grumbling about America's obsession with fast cars, not big ideas, can there be any doubt that Ronald Reagan and Ralph Lauren won? We now live in a Reaganized and Laurenified America.