"Let us remember the heroes of Warsaw, the martyrs fo Treblinka, the children of Auschwitz: They did not die alone, for something of all of us died with them."

In a clear voice that penetrated like a cold wind, Elie Wiesel summed up the Holocaust, 35 years after he endured it himself. The president, the Congress and hundreds of others crowded into the Capitol rotunda yesterday for a memorial "that no other country and its govrnment, besides Israel, has heeded."

This Saturday and Sunday have been designated Days of Remembrance by proclamation and resolution, and for this Wiesel expressed his thanks as chairman of the President's Commission on the Holocaust.

But then he asked why it had taken so long. During the war, he said, all sorts of underground groups were helped by London, Moscow and Washington. Not the Jews9

"The truth is, they were forgotten. The world knew-and kep silent. Pictures of Auschwitz and Birkenau had reached the world earlier, but nothing was done to slow the process. Not one bomb was dropped on the rail lines there . . .

"Had there been a joint session of Congress then, things would have been better for thousands of Jews," he added in mordant understatement. "The opposite of love is not hatred, but indifference."

The audience stood, hardly moving, whlie the high children's voices of the Atlanta Boys' Chor sang songs from the ghetto. When cantor Isaac Good-friend chanted the memorial prayer in Hebrew-you could hear the words "Auschwitz . . . Maidanek . . . Treblinka" in the rolling sonorities-some listened, as did President Carter, with eyes closed.

Carter later spoke of his visit to Israel, of how "like literally millions before me, I grieved as I looked at book after book, row after row, each recording the name of a man or a woman, a little boy or little girl each one a victim of the Holocaust.

"I vowed then, as people all over the world are doing this week, to reaffirm our unshakable commitment that such an event will never recur on this earth again."

The central lesson of the Holocaust, he said, must be the sanctity of all humankind and the knowledge that "each man's death diminishes me."

"To truly commemorate the victims of the Holocaust, we must harness the outrage of our memories to banish all human oppression from the world. . . . The World's failure to recognize that moral truth 40 years ago permitted the Holocaust to proceed. Our generation, the generation of survivors, will never permit that lesson to be forgotten."

Six candles of a menorah were lit by Wiesel, former Supreme Court justice and labor secretary Arthur Goldberg, and Murray Blinker, and Auschwitz survivor. A seventh candle was lit by Armenian leader Alex Manoogian in memory of the Armenian genocide victims, traditionally mourned on April 24.

Rabbi Bernard S. Raskas said the Kaddish, the Jewish prayer for the dead. (Wiesel had spoken of the Kaddish. He had told of watching people walk quietly to the death chambers, "those whose cemetery was the sky," reciting the Kaddish over themseves.)

As the ancient words rang out strongly in the echoing rotunda, people here and there in the audience joined him, and great murmur rose. CAPTION: Picture, President Carter and Elie Wiesel, by Frank Johnston-The Washington Post