For historians, hindsight can be a treacherous ally. Enabling us to trace the hidden patterns of past events, it beguiles us with the mirage of inevitability, the assumption that different outcomes lay beyond the limits of the possible.

Freedom has been privatized - it is how you dress, what your sexual orientation is, choosing your own life. That's fine. But that is not what Thomas Jefferson was talking about.

You pick up very well-known books on Lincoln [and] you will find almost no reference to his long-term belief in colonization. Why? Because it doesn't fit the image of the Great Emancipator. It doesn't fit the retrospective view we want to have of Lincoln as the man who was the moralist in politics, who came into office committed to ending slavery and waited to sign this document.

Colonization was the idea that once slavery ended African-Americans should be encouraged - or required, in some people's view - required to leave the country. It's part of an attitude toward the abolition of slavery which says America should not be a slave society, but it can never be a multiracial society. You can never have free black and white people living together.

Lincoln sees slavery in some ways as a theft of labor. A slave is a laborer who is being denied the fruits of his labor.

In the Shadow of Slavery covers two and a half centuries of black life in New York City, and skillfully interweaves the categories of race and class as they affected the formation of African American identity. Leslie Harris has made a major contribution to our understanding of the black experience.

A new future requires a new past.