It comes from a speech Emma Goldman was to give in Chicago on March 16, 1908, but she was arrested before she could speak and roughed up by the cops. The speech was titled "Anarchy and What It Really Stands For" and was printed in the Chicago Daily Journal on March 17, 1908. A few days after that, "Anarchy and What It Really Stands For," was published as a pamphlet under the title "A Beautiful Ideal" with a very minor tweak or two. UC Berkeley has a copy of the pamphlet on microfilm. University of Illinois probably has a copy of the original text on microfilm from the Chicago Daily Journal newspaper. I'm not sure on who came up with changing the name to "A Beautiful Ideal." My best guess is it was Emma Goldman herself, Ben Reitman, Johann Most, or Max Nattlau. Possibly a combo"Anarchy and What It Really Stands For" was tweaked again and re-titled "Anarchism: What It Really Stands For" in 1910. It's in Anarchism and Other Essays by Emma Goldman.