Keystone does a fine job of tracing the trajectory of this Irish-Catholic (rather than Jewish) movie mogul as well as what Louvish calls "Sennett's ... America, contagious, nervous, always at high speed."Quote by Sennett, from page 292 in Keystone: "I might add that I don't know anything about politics. I'm not a Communist. I'm an Irish Catholic. A requiem mass took place at the Church of the Blessed Sacrament in Hollywood, attended by all the usual suspects."
From: Gerald Mast, "Mack Sennett" in World Film Directors, Volume One: 1890-1945, ed. by John Wakeman, H. W. Wilson Company: New York (1987), page 986:
...[Mack Sennett] was born in Danville, near Richmond, Quebec, into a family of Irish Catholic farmers...Mast, pages 987-988:
The traditional ethnic traits of Ameria's urban and immigrant population provided another rich source of material. The American burlesque theatre was both a mirror and a product of immigration patterns, dominated by the stage Irishman (in the same eara as the shows of Harrigan and Hart and George M. Cohan), the "Duch" dialect comedians ("Dutch," slang for deutsch, usually meant Yiddish), and the "coon" shows (which grew out of earlier minstrel shows to become the performance rage early in the century). The dominant producers and performers of burlesque were generally Jewish--Joe Weber and Lew Fields, the Minsky brothers, the Howard brothers--and many would move from the cheap novelty shows into the infant movie business. By the more enlightened standards of today, the explicit jokes based on racial and sexual stereotypes wold seem unkind at the least and often grossly racist or sexist. Many Sennett films are so offensive in later American terms that they have not been shown for sixty years...
[page 988] More than anything else, Sennett provided the bridge that brought burlesque from the Bowery to Hollywood. For his characters, Sennett borrowed the usual burlesque assortment of ethnic stereotypes: Jews named Cohen, blacks named Rastus, Irish named Riley, Germans named Meyer, Schuultz, and Heinie, and country bumpkins, usually played by Sennett himself.