THIS SUMMER in South Africa a Black boy was standing in his room as the police were breaking up a crowd on the street below. A stray police rubber bullet broke through the window and hit the boy, bursting his eye and going into his brain.

Sometimes the news becomes more numerical than physical. Four Blacks killed by police. Hmm, we think, that's two more than yesterday. One more and the Sox clinch. We forget that those numbers are people, that those paragraphs are pain. That the boy was a real boy, with a real rubber bullet in his brain.

Last month, 177 Black workers died in a gold-mine fire, caused by the unsafe working conditions. An acetylene cylinder exploded, forcing workers to scramble out of the deep underground tunnels for safety.

Some didn't make it, and they were burned alive, fire scorching the skin from their hands and neck and face, peeling their legs. Think of what it's like to burn alive. "Blacks are paying with their lives," announced one Black worker's union, "for the wealth and profits in which they do not share."

IN WASHINGTON, Congress has finally rammed through Ronald Reagan's roadblocks and implemented sanctions against South Africa. But it is too little, too late. Congress has come clean just in time to take a bloodbath. "It will harm us, but it will not kill us," said South African Foreign Minister Roelof Botha of the impending U.S. sanctions.

Botha is right. Sanctions will not kill South Africa like its rubber bullet killed that boy. "Sanctions may hurt," said Rep. William Gray (D-Pa.), "But apartheid has killed over 130 Blacks every month since January and jailed without trial thousands and many have just simply disappeared."

Sanctions send a powerful and long needed moral signal, but the new sanctions will affect only 5 percent of South Africa's overall exports. In Johannesburg, stores callously advertised "pre-sanctions" sales. It is time for stronger methods.

Reagan has not hesitated to involve himself in the most questionable military exploits. Reagan was eager to send troops into Grenada. Reagan applauded the British invasion of the Falklands. Reagan has sent guns and money to Afganistan. Reagan has sent military aid to the contras in Nicaragua. Reagan has bombed Libya.

Now, when the cause is just, Reagan has offered no such help to South African Blacks. Half lame duck, half rabid dog, Reagan has backed into a corner, all alone in his stance for "non-punitive" measures against the Pretoria goverment.

The solution, Reagan said, lies in steps to "keep the United States at arm's distance from the South African regime, while keeping America's beneficent influence at work bringing about constructive change."

He's been doing that--and it has killed 130 Blacks a month. It is time to end the horror and hypocrisy of U.S. foreign policy. The U.S. should begin to send military aid to Black South African rebels. Congress has already chosen social change over small change by imposing the recent sanctions. Congress has realized that it won't matter how many Krugerrands it's stuffed in its pockets, if the gold mine's on fire.

Now Congress must accept the principle that the Black South African boy learned as the rubber bullet entered his eye and went into his brain: there are no uninvolved bystanders.

Reagan would have America be a super-power voyeur, sitting and watching as Botha and his apartheid regime rape the country. Congress must leave Botha to his peep-show and begin taking the real steps in freeing South Africa's Blacks--military aid. "Apartheid will be dismantled and its victims will remember who helped to destroy this evil system," said Bishop Desmond M. Tutu, "and President Reagan will be judged harshly by history."