Seduction is an especially fraught subject because we have long had trouble agreeing on what it is. Does it mean chocolate-dipped strawberries and a Quiet Storm playlist? Swiping right? Stretching provocatively at the gym? Sending pictures of your genitalia? Grabbing ’em by the you-know-what? Demanding a “massage” for a $200 tip — or the promise of movie roles?

It is a rich field for Clement Knox, our genteel narrator and a puppy-eyed 30-year-old nonfiction book buyer in London for Waterstones. At first, I assumed the author’s youth was the reason his history of the subject was so gargantuan, a near 500-page feat of millennial overcompensation. But I was wrong. Seduction is a grand theme, influencing politics and power, guiding history, shaping literature and forging powerful social movements.

Knox takes us through the lives of memorable seducers and their critics, in sometimes academic and sometimes rococo prose dappled with doges, coups de foudre, rakes, bawds, coquettes, coxcombs and procuresses — with guest appearances by members of the Frankfurt School sunning themselves in La Jolla.

Like an R-rated version of “A Christmas Carol,” Knox’s history whisks us from Casanova’s mirrored sex suite to the rake culture of London, where we meet Col. Francis Charteris, a serial predator of such distinguished loathsomeness that he was known by his nom de guerre, “the Rape Master General,” and was alleged to have even raped his own grandmother. But by his side we also have Samuel Richardson, whose novel “Pamela” was a blueprint for how chaste women should behave in the face of avid pursuit, encouraging a zeal for housewifery. Then it’s on to the St. Pancras churchyard, where the bachelorette Mary Godwin has sex with a married (and short and sickly) Percy Bysshe Shelley, and to the flapper parties of 1920s America, “where bootleg gin was served behind the bar and vomited up in the ladies’ room.” Later come the Nazis, who deployed propaganda about hypnotists, vampires and sexual monsters to stoke social and sexual panic against Jews.