YOU CAN BEGIN quoting Russell Baker in this collection, as you can begin reading him, almost anywhere. Open at random to "The Humble Dollar" (you will have to track it down; his latest book has no table of contents), and you come up with a small gem:

"The papers keep saying that the dollar is very weak. This is nonsense. The truth is that the dollar is absolutely powerless. I sent one out for a pound of cheese the other day and it was thrown out of the store for giving itself airs."

It's all there in that quote: the timeliness, the air of crisis, the sweeping generalization and the quick, absurd illustration that puts everything in context and makes you want to laugh. The Baker technique is easy to reduct to a formula when you have read enough samples. Fortunately for Baker, the formula is difficult to translate into living prose and almost impossible to implement on deadline, several times a week, with consistent quality, as Baker has been doing in his "Observer" column for The New York Times sinced 1962.

The hardest part is the requirement that it should be funny. Some writers have an endless supply of profundity, constantly available at five minutes' notice, but very few have professional-quality wit so readily on tap. Many of the most profound have no wit at all. Occasionally, Baker lets up on the comedy and settles for mere seriousness, but he is almost never solemn -- for reasons explained in one of the little essays in So This Is Depravity :

"Though Americans talk a great deal about the virtue of being serious, they generally prefer people who are solemn over people who are serious. . . . Jogging is solemn. Poker is serious. Once you can grasp that distinction, you are on your way to enlightenment."

Baker's form of enlightenment usually arrives in segements about 2 1/2 pages long -- just about right for the rushed, half-awake reader of a morning paper, though they make the continuity seem a bit choppy when spread out in a book. The brevity of its segments probably accounts for the smaller-than-usual design of So This Is Depravity, which is chopped down to the page-size of a trade paperback or a volume in the Viking Portable Library. The world probably isnht ready yet for a Portable Baker. He is consistently good and sometimes brilliant in the selections included in this book, but he'll have to wait a while to become a classic.

He does have one of the other qualities of a classic, however: the ability to take the random material of current events and find durable meaning in it. He does this partly through concrete images, which transcend such narrow categories as comedy and solemnity. Any abstract definitaion reduces the richness of his central image in "Spaced In," for example, which compared life in New York City to the behavior of a driver trying to park a 20-foot car in a 19-foot space. "Trying to fit life into spaces too small for it takes a toll on civilization," he says, and that observation totters on the brink of solemnity. But it doesn't fall over, because we have had several very concrete paragraphs showing a New York driver trying to make room for himself: "The front car declines to yield. He goes into reverse. Bashes rear bumper against rear car. Rear car shudders, leaps. Then -- gear in forward position -- slam on the gas -- bang the front car. Everything vibrates. Back he goes -- bang -- into the rear car. Forward -- boom -- into the front." This kills all danger of solemnity. It is something like poetry, which is always serious, even when it is comic, but stops being poetry when it starts being solemn.

The latest installmane in the continuing intellectual adventures of the "Observer" begins in 1973 -- just over a decade after the column began -- and it excorts the reader through the years of darkest Nixon and Ford up to the present, bouncing around the '70s like a supercharged pinball. The book's tone is set and its title adumbrated by a Latin quotation from Juvenal which has a page all to itself at the begining: Nemo repente fuit turpissimus (roughly, "It takes a while to become utterly depraved"). If you want to sum up the '70s in four words, those may be a good as any.

Baker takes another 300-odd pages to elaborate and annotate Juvenal's pithy observation -- not that Baker lacks pith, but English is a workier language than Latin, and there are so many points to be covered -- some quite ugently. A theme for 1980, though it was written four years ago, is his observation on those who abstain from voting because they are "too high-minded to concede that politics is almost always the choice of the lesser evil."

"Consider all the people who sat home in a stew in 1968 rather than vote for Hubert Humphrey," he says. "They showed Humphrey. Those people who taught Hubert Humphery a lesson will still be enjoying the Nixon Supreme Court when Tricia and Julie begin to find silver threads among the gold and the black."

Baker is good all through the book on the potentially disastrous effects of high-mindedness -- fortunately, since it was a leitmotif of the decade which he loosely chronicles. He has a keen eye on the way people live in television commercials -- on the men named Buck and Mike who are forever dropping their tools and running off for their after-work beer, and on the competition between headach, upset stomach and nagging backache for the status of No. 1 medical problem. The evils of jogging -- particularly of jogging others out of their pet vices -- move him to put down his martini and his cigarette long enough for a serious (though not solemn) warning. A weakness, I think, but one into which he does not fall too often, is his occasional use of the historical flashback -- a piece showing how George Washington would have acted in situations typical of Richard Nixon, or a portrayal of Henry James using his fists like Norman Mailer. These fail to be funny, perhaps through sheer implausibility, but being funny is not his only strength. In this collection, he is particularly eloquent on American money -- perhaps because of the horrible things that happen to it in the '70s. There is acute psyco-economic observation in an essay about the turning point that came when he started unconsciously stuffing dollar bills in his pocket like coins, rather than put them in his wallet. And there is a special kind of poetry in an essay about old people shopping -- trying to pay '70s prices with money earned in the '60s, deliberating on whether to buy one orange and finally putting it back.

The bedrock of his subject-matter is politics, and he tries to be even-handed about it. "The Democrats have no program" he observed during the 1976 campaign. "Actually, the Democrats may not be a party anymore. I tend to the theory that they are just a memory." On the other hand, "To a Republican, a Republican President is not good enough. He must be The Right Kind of Republican President. The Right Kind of Republican President is the kind for whom independents and Democrats will vote only if the alternative is Attila the Hun."

Both passages, like most of the other material in this book written for nearly a decade of deadlines, seem designed to stand at least a medium-length test of time.