Context
Traveller vs. tripper
Chesterton drops the line in a chapter about his lecture tours and his lifelong habit of “pottering about” France since boyhood. His point is not snobbery about who can afford to travel — he calls the distinction “one rather of epoch than education” — but about attention. The traveller lets a place surprise him; the tripper arrives with a checklist and notices only what confirms it.
The aphorism has outlived its own vocabulary. “Tripper” — the day-excursionist of Edwardian England — faded from speech, and quoters reached for “tourist,” which sharpens the modern travel-versus-tourism cliché the line is now used to endorse.
The traveller sees what he sees; the tripper sees what he has come to see.