EVERYBODY COLLECTS something, and we collect sentences that appear in this newspaper. Certain sentences, that is - sentences that are a comment on the legal and social structure of our times and which we like to imagine a baffled, beleaguered posterity trying to figure out.

One of these leapt out of the Sunday paper at us. It contained this most arresting, even transfixing phrase: "Washington, the nation's premier black city, with a minority population of more than 70 per cent . . . " A "minority" population of more than 70 per cent? Well, yes. But that, as you might say, wasn't the half of it, since it presumably left the nation's capital with a "majority" population of less than 30 per cent. To read that is to know you are in the presence not just of a collector's item but also and more importantly of the new (racial) math.

For once we are not blaming a journalistic colleague here: You can hardly blame the press for using a term that is the self-definition of choice of so many people and that, in addition, has found its way into the bureaucratic and official lexicon. We also will concede that we know that the term "minority" in this context is a racial designation; that, to the extent that it retains any meaning at all, it refers to racial groups that add up to a minority of the total nationa population; and that what began as a fairly precise social and legal concept - i.e., the need to ensure the rights of a racial minority that had historically been repressed by the majority - has now slid into the official paperwork language of the day. It has become a kind of convenient circumlocution that seems to mean less as it is used more.

But there are reasons for speaking in direct and accurate language. The news story that spoke of the District's 70 per cent population, for instance, dealt with the difficulties blacks face in getting capital to start business. Surely the actual point about the discrimination involved is only revealed when you consider that an overwhelming majority population in the District accounts for ownership of only about a third of the District's businesses.

There is a legal reason for plain-speaking as well. Although for the bureaucracies' "minority" may be just a term of convenience, when you rest your case for taking certain actions on the minority status of citizens who in fact represent a majority, you are courting trouble. many of the most difficult racial issues of our time need to be worked out within local jurisdictions - school district, subdivision, city, county, state. It is not whimsical to suppose that if the minority condition of some citizens is made the justification and test for certain civil-rights programs and benefits, then sooner or later we will get a new and different though equally disruptive "Bakke case," one that seeks to hold the authorities to their literal word.

It may cost us a volume or two in collected imponderables from the daily paper, but the sacrifice would be well worth it: We think clarity, sense and sensible action all would be served if in racial matters, anyway, the bureaucracy and the rest of us would cut out the romance, say what we mean, try to describe reality more or less as it is - and go back to the old math.