"THE WINDS are changing; the bloom is fading from false mandates," labor chieftain Lane Kirkland said Saturday. And the size of his audience lent credence to his words--close to 300,000 trade unionists were crowded onto the Mall in our nation's capital to say they were sick already of President Reagan's economic policies.

It is true that Reagan, a skilled campaigner, managed to fool many last November, garnering votes from people of every class and background who should have known better. But Solidarity Day proves two things--many of those who were taken in have realized their folly, a realization aided by decisions like the current effort to slash the size of school lunches for poor children. And more, many of those people are now willing to do something concrete about their dissatisfaction.

Labor has led in this endeavor, but it is up to others to follow. Students were conspicuous by their absence Saturday, although Reagan's destructiveness will hurt us as much as any group. Others should join in the spirit of Solidarity, so that, as in Poland, it comes to mean more than brotherhood by occupation. If the stand against Reagan is to be a success, Solidarity can mean nothing less than the stand of all the humane and all the oppressed against all the bosses of our society, be they in industry or government.