NEW YORK (CNS) -- Understandably, Phineas Taylor ("P.T.") Barnum, whose name is practically synonymous with the big top, figures prominently in PBS' marvelous and engrossing documentary "The Circus."

Part of the 30-year-old and highly regarded "American Experience" franchise, the four-hour film airs over two consecutive evenings, Monday, Oct 8, and Tuesday, Oct. 9, 9-11 p.m. EDT each night. (Check local listings.)

Sharon Grimberg writes, produces and directs "The Circus" with care -- and with obvious affection for this wondrous, appealing and long-lived form of popular entertainment. However, she also critically examines the circus world's less savory and more controversial aspects.

Commentary from more than 20 writers, historians, curators, performers and family members inform the narrative, which traces American big top-style circuses from their late 18th-century origins in Philadelphia to the Ringling Bros.-Barnum & Bailey Circus' final performance under a tent in Pittsburgh in July 1956.

Exquisite still photographs and archival film footage -- signature elements in any "American Experience" presentation -- as well as the inclusion of distinctive circus illustrations augment viewers' experience. Actors' recitations of writings evoking the circus' mystique from poet Emily Dickinson and authors E.B. White and James Baldwin, among others, also enrich the storytelling.

Circus troupes left their winter quarters in the early spring, and returned in the fall, traveling "every day, as far as a horse could pull a wagon." "These rituals of itineracy," as University of Texas at Austin American studies professor Janet Davis says, established "a way of 'circusing' that was distinctly American."

The advent of cross-country train travel in the 1870s transformed the circus into an "entertainment-industrial complex," as Robert Thompson, Syracuse University professor of television and popular culture, notes. In its first nationwide train tour in 1872, the largest circus of its day, Barnum and Bailey's, traveled 7,000 miles in five months, making 146 stops and grossing $1 million.

The first episode details the parallel, equally up-from-nothing ascent of the two most dominant showmen of the 19th century: Barnum and James Bailey. Barnum was left destitute at 15 when his father, a Bethel, Connecticut, innkeeper, died in 1826. Yet his knack for exploiting sideshow attractions eventually made him the "most widely known and visible American of the 19th century."

Born James McGinnis in 1847, the future Bailey, an orphaned 13-year-old, was working as a bellboy in Pontiac, Michigan, when he met circus advance man Fred Bailey, who hired young James as his assistant. Through Fred, James acquired his new surname and his special gift for promotion, which eventually prompted Barnum to call him "the most genius impresario in show business."

Conceding he could no longer outdo his rival, Barnum merged his circus with Bailey's in 1881. Beginning in 1897, Barnum and Bailey's triumphant, five-year European tour left room, back in America, for seven brothers from Baraboo, Wisconsin -- Al, Gus, Alf, Otto, Charles, Henry and John Ringling -- to stake their circus' claim as "the greatest show on earth." The Ringlings' story dominates the second episode.

After Bailey's 1906 death, the circuses united in 1907, adopting the moniker by which all now know it. According to circus historian Fred Pfening, the Ringlings were the "best circus managers in American history." However, rising costs, labor strife and, most especially, television's ascendancy led to the big top's gradual demise.

"The Circus," rated TV-PG -- parental guidance suggested -- contains depictions of animal cruelty, racial exploitation, brief cultural nudity and one mild sexual innuendo. It makes acceptable viewing, accordingly, for adults and mature adolescents.

To its credit, the film doesn't shy away from the genre's more questionable aspects, such as the presentation of sideshow performers and the treatment of animals.

The documentarians lament the racial exploitation involved in sideshows, some of which, for instance, depicted Chinese people, as "oddities." Additionally, those with deformities -- like armless woman Ann Leak -- were exhibited for profit.

Viewers also will encounter troubling images of animals in chains and being whipped. Concerns about caged animal acts compelled John Ringling, for a time, to forbid them. Generations later, similar complaints from activist groups like People for the Ethical Treatment of Animals contributed to the 2017 final shutdown of the Ringling Bros.-Barnum & Bailey Circus.

Though tough-minded, the program also shows a fondness for performers like aerialist Lillian Leitzel, "the greatest superstar the circus has ever seen," according to historian Richard Reynolds. By reintroducing viewers to such figures, whose astounding feats enthralled their forebearers, "The Circus" succeeds magnificently.

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Byrd is a guest reviewer for Catholic News Service.