Kirby's guest this hour is Joshua Muravchik- author of Heaven On Earth: The Rise and Fall of Socialism. Socialism was man's most ambitious attempt to supplant religion with a doctrine claiming to ground itself in "science." Indeed, no religion ever spread so far so fast. Yet while socialism had established itself as a fact of life by the beginning of the 20th century, it did not create societies of abundance or give birth to "the New Man." Each failure inspired new searches for the path to the promised land: revolution, communes, social democracy, Communism, Fascism, Third World socialism. None worked, and some exacted staggering human tolls.