march to (the beat of) a different drummer, to

Fig. to believe in a different set of principles. John is marching to a different drummer, and he doesn't associate with us anymore. Since Sally started marching to the beat of a different drummer, she has had a lot of great new ideas.

To follow principles quite different from those of most others. This term, which became current in the mid-twentieth century, actually has its source in the last chapter of Thoreau’s Walden (1854): “If a man does not keep pace with his companions, perhaps it is because he hears a different drummer.” Thoreau, champion of individualism, was hailed by the antiestablishmentarians of the 1960s in particular, who picked up a version of his phrase. Quoting a business executive, Connie Bruck wrote in a 1990 New Yorker article, “We saw ourselves . . . as the tough guys, very smart, who were marching to our own drummer.”