“In the new edition, I have also included some speeches given by Groucho. Since he wrote them without any intention of publishing them, I did not consider them for the original edition. But over the years, I enjoyed reading them so much that I decided they belonged in the collection. Groucho’s writing style is so conversational that the speeches seem like they were written for publication.

“My methods for finding some of this material are purely unscientific. In some cases, I simply skimmed through every page of a post until I found Groucho’s contribution. I spent many hours in libraries reading 1930s magazines like Judge and College Humor, which were never indexed. As you might expect, I also found a few other interesting articles. I consider that time very well spent. And the process has saved some small treasures from Groucho.

“I’ve read virtually every book ever published on the Marx Brothers. I’ve even written about them myself. Robert Bader’s book is a revelation,” wrote Leonard Maltin, in an endorsement.

As Bader traces the origins of characters who would later be loved by moviegoers, he also deftly weeds out the buildup of rumors and mythology perpetuated not just by fans and writers, but by the Marx Brothers themselves. Revealing, vital and entertaining, Four of the Three Musketeers will establish itself as an essential reference of this emblematic American number.

The documentarian has a fluid take on his favorite fun movies, a virtual monkey soup.

“Like many Marx Brothers fans, I love all five Paramount films — their firsts,” Bader said. “It would be ridiculous to say they were funnier with Zeppo, but I love seeing the Four Marx Brothers because that’s how they became stars on the vaudeville scene. We can see them as relatively young men in these films.