In this context, "mop, and mowe" means 'a grimace'.
The term trip in this passage means to step lightly or nimbly. The adjectives light and fantastick (as Milton spelled it) refer to the movement of the feet (toe, or dance step).
A variation appeared in the poem "Jim Brown" by Edgar Lee Masters, part of his Spoon River Anthology. It appears in a list of activities that divides men into camps for and against. In the poem it is not tripping, but skipping the light fantastic.
The phrase 'trip the light fantastic' has been used in several modern contexts. One of the more interesting evolutions of the phrase is in the 1960s ballad A Whiter Shade of Pale, by the rock group Procol Harum.
The phrase is used in the second line of a 1927 song by Billy Murray and Aileen Stanley - 'I'm Gonna Dance Wit da Guy Wot Brung Me' - a comical duet between two New York types using one slang phrase after another in a vaudeville-like routine. The manner in which the phrase is used, suggests that 'tripping the light fantasic' was a not unusual bit of Roaring 20's slang.
On her album "Island Life," Grace Jones incorporated the phrase in the song "Walking in the Rain:"
Another appearance is in the 1997 film "L.A. Confidential" when the character of Sid Hudgens (played by Danny DeVito) refers to two young pot-smokers as "tripping the light fantastic." In this instance the phrase is used ironically and plays off the contemporary slang usage of "trip" referring to taking drugs, specifically hallucinogenics. This updated meaning of the phrase is made possible by the earlier truncating of "toe" off the end, so that "trip the light fantastic toe" becomes simply "trip the light fantastic," where "light" and "fantastic" cease to modify "toe," and now "fantastic" simply modifies "light." The new meaning that now arises from the phrase is to take a mental journey on hallucinogenic drugs.
A similar usage is employed in Terry Pratchett's second Discworld novel, The Light Fantastic, which describes the opposite of light, but not darkness—rather something that is as far from darkness as normal light, but in the opposite direction.
The phrase appears in the
The phrase also appears in 1979 BBC television mini-series adaptation of Tinker, Tailor, Soldier, Spy: "Tripping the light fantastic through the whitehall corridors"
It occurs in David Crowder and Mike Hogan's book Everybody Wants to Go to Heaven But Nobody Wants to Die (page 72): "Science and the soul have been tripping the light fantastic together for some time now."
UK pop singer Sophie Ellis-Bextor named her third album "Trip The Light Fantastic" in a probable reference to the original meaning, as she moves rather lightly when performing. She's said it essentially means "to dance"
In Dean Koontz's Life Expectancy (2004, p. 320), the protagonist references his newly acquired dancing ability: "Consequently, I learned to trip the light fantastic better than I had imagined that I could, considering that I'm biggish for my size and something of a gimp."
The role-playing game Bureau 13: Stalking the Night Fantastic draws its name from the phrase.
The band 311 (band) makes reference to this phrase in the lyrics from their song "Loco": "We trip the 'shrooms fantastic."
The band Weatherbox plays off the phrase in the title of their song "Tripping the Life Fantastic."
The phrase is also used by Bing Crosby in the song 'St. Patrick's Day Parade'.
The phrase appears in the song "Barrier Reef" by The Old 97's
This phrase is also found in a line of gibberish spoken by a man under the influence of a drug in Isaac Asimov's short story "I'm in Marsport Without Hilda" (1957): "Trip the light fantastic tock the clock is crowings on the bird."
In George Saunders's novella Bounty (1996) the phrase is used referring to the main character, Cole. "The real me was out there in tights, tripping the light fantastic for a bunch of soused rich vacationers."
The phrase is also used as a song name, by the band Chinastyle. The single is due to release on April 28th 2008.