Janus, the Roman god of doors, gates, and all beginnings, is invariably depicted as having two faces--one to look back and another to look forward. In this earnest if impressionistic effort to come to grips with the socioeconomic state of the nation, Shames (The Big Time. 1986) adopts much the same stance, reviewing the recent past and divining the immediate future. As a practical matter, the author concludes, the US is about as wealthy as it's going to get. Consequently, he argues that a populace whose forebears took endless frontiers for granted must now accept the fact of limits. By his reckoning, the new reality of diminished expectations became clear following the stock market's 1987 break. But Shames (a former ethics columnist for Esquire) does not deem the passing of an era celebrated largely for the conspicuous consumption of its so-called yuppies as an occasion for mourning. Indeed, he professes to welcome the opportunity to become what President Bush in another context called a ""kinder, gentler"" society, one in which success is measured by other than monetary standards. While there's no gainsaying the author's sincerity, his analyses have a carriage-trade bias. Wittingly or not, he's addressing the anxieties of the affluent; working-class concerns, which tend to center on job security rather than upward mobility, are accorded relatively short shrift in his appraisal of the harder times to come. Nor does Shames shy from the moral equivalent of literary manipulation. Throughout, his commentary is counterpointed by a narrative account of the pseudonymous ""Colliers"" before and after October 19, 1987. Residents of Manhattan's Upper West Side (with a weekend home in the country), these young, handsomely compensated professionals are utterly atypical. Their inclusion seems calculated mainly to give Shames the chance to close on a hopeful set-piece note--the birth of the couple's first child. Value judgments, informed by a genuine sense of decency, on the vulnerabilities of the US and its pace-setting citizenry.