The literary critic, theorist and Shakespeare scholar Stephen Greenblatt’s new book, “The Swerve: How the World Became Modern,” is partly about an obsessive book collector, and it begins, appropriately enough, with a book purchase of the author’s own.

In the mid-1960s, when he was a student at Yale and searching for summer reading, Mr. Greenblatt came upon a prose translation of Lucretius’ 2,000-year-old poem “On the Nature of Things” (“De Rerum Natura”). He plucked it from a Yale Co-op bargain bin for 10 cents, partly because he liked its sexy cover, a pair of disembodied legs floating above the Earth in an apparent act of “celestial coition.”

Mr. Greenblatt read “On the Nature of Things” that golden summer. The book spoke to him for a reason that’s straight out of a Woody Allen movie or a Bruce Jay Friedman novel: because of his own overbearing Jewish mother. “The core of Lucretius’ poem is a profound, therapeutic meditation on the fear of death, and that fear dominated my entire childhood,” Mr. Greenblatt writes. It wasn’t a fear of his own demise that troubled him. It was his mother’s “absolute certainty” that she was going to be stricken at any moment.

She’d stop on the street, as if about to keel over from a heart attack, and ask the young Mr. Greenblatt to touch the “vein pulsing in her neck.” At moments of parting there were “operatic scenes of farewell.” Mama, enough with the drama! you can practically hear a weary Mr. Greenblatt bleat.