LIFE MAGAZINE returned to publication this week, almost six years after Time Inc. closed it down in 1972. There was much sadness expressed at the time, and there is much joy expressed now at the sight of the white LIFE, in bigger letters than the old, encased in the old red box with a new white border. The magazine, now a monthly, feels the same in your hands, and the articles - though insistently up to date - have the same old variety. Nothing has changed very much but the world; and therein lies Life's problematic future.

For what has happened to Life is that the phenomenon it started and sustained, for 1,864 issues, has overtaken it, turning what was a pioneer into something that risks becoming an anachronism. The headline of its editorial this month is "The Power of the Picture." And from 1936 on through the 1950s there was no medium in the world, let alone a magazine, that so demonstrated the power of the picture as Life. That simply is no longer so. There is television, for one thing. There are plenty of other publications around, including those of Time Inc., that depend on the strength of the visual image. And there is photography itself, which in the past 10 years has risen from a hobby to an art that is practiced by practically everyone.

So we look at the new Life with a half-sentimental curiosity, wondering how it can hold its own, how the power of the picture can hold its own against the competion it itself engendered. the answer should lie in the contents. But it is hard to whip up enthusiasm for a spread of pieces that jumps almost giddily from Jackie Onassis to the shah to the pope to Brooke Shields to a shot (the best in the issue) of Halston and Liza Minnelli exchanging grins in a showroom high above St. Patrick's and the rest of the steely Apple. There is too little in this issue that we do not get in other places. And since other places give us pictures, too, "Life" has made its task more difficult.

Yet the editors acknowledge the task: "The readers' increased awareness and knowledge sharpen the editors' need to select with care." May they do so from here on in.