Aloha, Kim. Odd coincidence--I have just completed 1866 in my comprehensive chronology, "Mark Twain, Day-by-Day," and have read all 25 letters of Sam's to the Sacramento Union. Yes, I believe it was Sanborn who compared the use of an alter-ego, in this case "Brown," to Sancho Panza. The source of the name "Brown" is, I believe, William Brown, the Mississippi Steamboat pilot: E2809Ca middle-aged, long, slim, bony, smooth-shaven, horse-faced, ignorant, stingy, malicious, snarling, fault-hunting, mote-magnifying tyrant," Who Sam had to "pound some" in that tiff on June 3, 1858. The alter ego literary ploy was used by Sam with his rival in Virginia City, Clement, whom he called "Unreliable." Sam loved a spoof, and also loved to exaggerate. Carrying a grudge wasn't beyond him either. Sam used people he'd known or met in so many of his stories. William Brown the nasty riverboat pilot was only one, but one who was vivid in Sam's memory. The Brown of the Union letters allowed Sam to make fun of customs, natives, habits and the like without taking the heat for it. Such poking fun of foreigners gave the home audience a secure and high-minded reassurance. The contrast with Brown allowed Sam, the reporter/narrator, to be seen in a more favorable and acceptable light. So, yes, I agree with Sanborn that Sam's use of Brown, is indeed an alter-ego sidekick. In the Sagebrush Bohemian, Nigey Lennon wrote, "Just as he had used Clement Rice as 'The Unreliable' to good advantage, Twain created 'Mr. Brown,' ostensibly his traveling companion during the Sandwich Islands jaunt, but in reality a catchall for every crude impulse Twain himself experienced and was ashamed to call his own." p123. I'm not so certain that Twain was ashamed of much--but this gave him a way to express some of his crude humor without pissing off the editors and readers of the Sacramento Union, from whom Sam depended on a living over the next five months. In my research I discovered that Sam wrote many of the letters days after the fact, or when he'd returned to Honolulu. He even dated one "September 10th" when he left the Islands aboard the sailing ship Smyrniote July 19th 1866. Hope this helps, David H. Fears Mark Twain, Day by Day - a comprehensive, daily chronology in progress