While Edward Gibbon was publishing his six-volume opus, “Decline and Fall of the Roman Empire,” a large portion of Britain’s empire was declaring its independence and fighting to break free of the mother country.

The first volume of Gibbon’s history was published in 1776, just months before representatives from the 13 American Colonies met in Philadelphia to sign the radical and audacious document that declared, “All men are created equal.” While not quite “the shot heard round the world,” Gibbon’s history immediately captured the attention of the reading public and became a best-seller. Harvard acquired its copy in 1790.

Looking at the antiquated typography and faded penmanship on display in a new exhibit, “The Luminous Historian: Edward Gibbon in the Collections of Houghton Library,” organized by John Overholt, assistant curator of the Donald and Mary Hyde Collection, it is well to remember that Gibbon’s work emerges from a period of great political and intellectual turmoil. The Enlightenment, whose ideas fueled the American Revolution, inspiring leaders to throw off thousands of years of aristocratic rule and set up the world’s first constitutional democracy, informs Gibbon’s history as well.

Not that Gibbon favored the American cause; he didn’t. But his Enlightenment perspective led him to view another sacred institution, Christianity, with critical detachment and to question whether its long-established dominance over European culture was altogether a good thing....