AMID THE GIUTTONY Thanksgiving can often prompt sincere reflection and thankfulness for both the material and spiritual means of wellbeing. So it was more than appropriate when several political leaders sacrificed their personal holidays to protest on behalf of an oppressed people who have neither

Three Black leaders--Rep Walter E. Fauntroy (D-D.C.). Civil Rights Commission member Mary Ann Berry, and Transamerica Executive Director Randall Robinson--launched a sit in at the South African embassy in Washington to call for the release of two recently tailed Black South African labor-leaders. The three were arrested on charges of illegal entry and spent the night in D.C. jails before their release on Friday.

The politicians, like the more than 100 demonstrators gathered outside the embassy during the sit-in could not have chosen a more crucial time to show support for South African Black. The white South African government has recently lightened its controls on Black political activity, resulting in the jailing--and in some cases death of ever greater numbers of Blacks there. At the same time, Reagan has not so much as tinkered with its policy of "constructive engagement" toward South Africa a policy--a policy that seeks to prompt liberalization in that country by cooperative, rather than confrontational measures. To date that approach has gone hand with increased racial violence and a constitution granting limited representation to Indians and "Colored" while continuing to exclude Blacks from political participation

USING THE LEVERAGE of U.S. investment "constructive engagement" aimed to shove South Africa towards real democracy. But the Reagan administration has been content to leave the "constructive" out of the "engagement." And in an U.S. administration committed first and foremost to stemming, communism in Africa, as elsewhere, and to protecting business interests, it is unlikely that the next four years will see any move toward a forceful, human rights policy toward South Africa.

The Washington protest, then, is an urgently needed effort to keep the pressure on both Pretoria and Foggy Bottom to launch a more principled approach to racial conflict in South Africa. At a news conference following the sit-in, protest organizers pledged to launch a national effort to force change on behalf of South Africa's Blacks and other minorities. We on campus must follow suit with continued calls for Harvard's divestiture and educational campaigns.

Administration officials will no doubt seize upon the Reagan "mandate" as license for the continuation or even expansion, of the opportunistic policy of collaboration with the South African government. If Reagan's reelection has thwarted hopes for any substantive redirection of U.S. South Africa policy, we surely cannot fail to stem this immoral tide of our foreign policy.