The nation’s birthday would seem to be a good time to consider the possibility of changing the way we have begun to think about America’s history. In our colleges and universities, too many people, from professors to students, are taking a moral approach to the past. They are judging previous generations whose attitudes and customs were often quite different from ours by the standards of today. The result has been a growing sense of guilt for the supposed failures of theseAmericans to live up to our contemporary ideals.

The prime example is slavery. Most people see it as a totally reprehensible social system for which it is impossible to forgive the white masters. Contemporary critics regularly fail to understand slavery’s deep roots in the world’s history. Does anyone know that in the eighth and ninth centuries tens of thousands of white European men, women and children were dragged into slavery by triumphant Muslim raiders who ruled the Mediterranean world? If we go back another thousand years we find slavery an essential part of the economy and social life of Greece and Rome.

When British, French and Spanish merchants began importing black slaves from Africa to the New World, no one took a moral view of it. They saw only another phase of an ancient system. The English city of Liverpool was so proud of the riches they accumulated from the slave trade, they included a chained humbled black man in their official city emblem. In Africa most of the slaves were captured by fellow blacks who marched them to the coast for sale to white traders. Morality had nothing to do with any part of this system. It was a simple business transaction. Is it surprising that for the better part of two centuries after the 1619 arrival of the first slaves, no one in the 13 British colonies except a handful of Quakers saw anything wrong with the custom?

Women and American Indians are two other groups whose pasts are being viewed with the same or similar searches for grievances. Forgotten is the huge cultural gap between European whites and the Indians, who did not even have a written language when the two groups collided in America. Also forgotten are the remarkable women who distinguished themselves as partners with their husbands across the broad spectrum of American life, from publishing newspapers to managing inherited businesses to participating in the politics that led to independence for America.

At least as important is the need to remember the millions of foreign-born men and women who streamed across the oceans in search of a better life in America. Almost all of them encountered prejudice and suspicion at first. They were helped by America’s prevailing philosophy in our first three centuries—assimilation. The newcomers were urged to abandon their old identities, including their native languages and many of their customs. Instead they were promised new pride and fresh hope as citizens of this huge and growing nation, with its ideals of universal freedom and fundamental equality.

For some time now assimilation has been on a collision course with historical victimhood. The grievance collectors question whether it is wise or just to urge people to surrender their original identities. Countries like Canada, which has become a collection of ethnic groups with their own education systems and languages – the French being the largest and most aggressively insistent on preserving their culture – are being held up as an alternative. But not a few people point to Spain, where the Basques are threatening secession, and Scotland, where ethnic identity is pushing for semi-independence from London, as evidence that this approach is full of potential dangers. Anyone who reads George Washington’s Farewell Address knows how crucial America’s union is to our peace and prosperity.

Is there an answer to this dilemma? I have found one in my research into America’s revolutionary decades. There I encountered the leading Irish-American of 1776, Charles Carroll of Maryland. He was one of the richest men in America. Yet he unhesitatingly risked his fortune -- and his life -- to sign the Declaration of Independence and support America's struggle for liberty.

Charles Carroll knew what would happen to America if England got her aristocratic foot on its prostrate neck. In Ireland, the Carrolls had been wealthy and distinguished – until the British reduced the Catholic Irish to humiliation and beggary. The Carrolls fled to America, where their business talents enabled some of them to regain their lost status, after not a few decades of hardship. Yet Charles Carroll did not preach hatred of England, either during or after the Revolution. He lived by a remarkable motto: "We must remember -- and forgive."

Carroll was enunciating a philosophy that was admirably adapted to the new country that he had helped to invent. He was telling Irish-Americans that it was important to remember their experience of British injustice. But forgiveness was vital because without it, they would be mired in miasmas of resentment and dreams of revenge, instead of turning their faces to the dynamic future that liberty was unfolding in America.

Remember and forgive. It might turn out to be a good formula for resolving a lot of the tensions that are threatening America's unity today. It allows us all to retain our ethnic and racial identities -- without foregoing our American lives. It enables us to reject the crippling hatreds preached by some people in the name of history’s grievances. I can’t think of a better day to suggest we embrace this philosophy. Why not give ourselves a birthday present that will make the pursuit of happiness a genuine possibility for everyone?