Certain adages exist about historical repetition: those who don’t remember the past are doomed to repeat it, for example, or history doesn’t repeat itself but it does rhyme. Walter Johnson doesn’t necessary believe in these old chestnuts, but he does see how the past and the present can illuminate one another in order to provide each greater context, urgency, and understanding.

Johnson, 40, a new professor of history and professor of African and African American studies in the Faculty of Arts and Sciences, is a historian of slave markets and the American South, particularly the lower Mississippi Valley. In his work, he imparts an intimacy and humanity to the study of this iniquitous time in American history as well as draws parallels to contemporary human suffering.

Johnson grew up in Columbia, Mo., and has subsequently spent time in both the North and the South. More recently, he lived in Manhattan for 12 years, where he headed the American Studies program at New York University. Now, after coming to Harvard, he resides in Cambridge with his wife and their two children, Giulia, 8, and Luca, 6.

Johnson finds Cambridge to be quiet, and sometimes misses the bustle of metropolitan life. However, he points out that for a family with young children, Cambridge has its virtues, including a winter with abundant snow and opportunities for sledding. The backyard’s nice, too, and so is the ability to go outside without worrying about an elevator and a doorman.

In his scholarly work, Johnson’s goal in writing about the enslavement of African-American people is to elucidate a part of American history that, to some extent, has been made familiar through historical tools that don’t preserve slavery’s visceral impact. Additionally, by illustrating both the humanity and the cruelty of this period, he hopes to draw parallels to current events and instances of contemporary human suffering.

“Today, our eyes are filled with images of extraordinary brutality and wanton disregard for humanity — whether it’s September 11, New Orleans after Hurricane Katrina, or Abu Ghraib,” says Johnson. “There is a set of images of how human beings behave to one another that I am trying to carry into my work on slavery, and to use my work to reflect back upon the violence and the brutality that have become so familiar today.”

Johnson says that current political leaders often frame the history of slavery in the United States as a prehistory to freedom. However, freedom did not evolve automatically, but has been actively produced by servitude and its aftermath, a nuance that necessitates a more critical examination of our own freedom. Even today, he continues, there are 27 million slaves in the global economy, which challenges the veracity of a narrow and linear definition of the trajectory of slavery.

Johnson finds compelling resonance between what happened in New Orleans in the aftermath of Hurricane Katrina and the history of enslaved African Americans. Perhaps more important, he sees how the two events provide context for one another, underscoring the urgency and tragedy of both situations. He points out that Jesse Jackson, in the aftermath of Hurricane Katrina, compared the Ernest N. Morial Convention Center to a slave ship, citing the disregard for black humanity in the convention center.

“When Jackson called the convention center a slave ship, he defied the notion of a history that proceeds naturally from slavery to freedom,” says Johnson, “replacing it with a notion of historical process that was something less than a strict repetition, and yet something more than a mere metaphor, something more akin to a notion that history does not simply pass or progress, but it accretes. And so for me that was one of these powerful instances of how the term ‘slavery’ has this tremendous power to make injustice visible.”

He goes on to say that this connection offers insight into what happened at the convention center by extending it beyond an isolated series of events in New Orleans.

“These events happen in different ways, Jackson was saying, but always to the same people. In some ways, this is a model for the way that I try to make connections,” says Johnson. “To use the visceral images of brutality to which we are gradually becoming habituated to write about slavery in a way that more effectively conveys the violence of the past, and, conversely, to use the history of slavery to mirror this moment and allow us to reflect on our own times and our own selves in a different way.”

His first book, “Soul by Soul: Inside the Antebellum Slave Market” (Harvard University Press, 1999), is a detailed account of the slave trade between 1820 and 1860, when 1 million people were transported between Maryland and Virginia to Alabama, Mississippi, and Louisiana. To research this book, he lived for a year and a half in New Orleans, the site of the largest slave market in North America, where he pored over the large body of commercial litigation developed by the slave trade, as well as first-person narratives of former slaves.

Johnson describes the work as analysis of economic history through the tools of cultural history. By stripping away the romanticism that had still existed in the literature of white Southerners, he writes about the history of the South in a way that is complex and intimate.

Currently, Johnson is working on a second book about the lower Mississippi Valley, one that he hopes will serve as a history of enslaved people extending beyond the paradigm of agency and resistance that has defined so much of slavery studies. Here, he examines not only the political and economic events that shaped the period, but also accounts of the humanity of enslaved people, and the economic ramifications of human suffering.

He also seeks to understand the world in which slaves lived, and to craft a history of their experience that incorporates the entirety of their experience as enslaved people. His intention is to place the social history of slavery in dialogue with questions of political and economic power, without diminishing the importance of the history of resistance. By asking these questions about social history it’s possible to see enslaved people as historical actors in a way that has revolutionized the study of slavery, he explains.

“Slaves lived in a world that exists as part of a full spectrum of human emotion — love, laughter, suffering, hunger, cold — which were powerfully conditioned by, but not reducible to, the terms of slavery,” says Johnson.