"The Rheinische Zeitung, which cannot concede the theoretical reality of communist ideas even in their present form, and can even less wish or consider possible their practical realization, will submit these ideas to a thorough criticism. If the Augsburg paper demanded and wanted more than slick phrases, it would see that writings such as those of Leroux, Considerant, and above all Proudhon's penetrating work, can be criticized, not through superficial notions of the moment, but only after long and deep study. We consider such 'theoretical' works the more seriously as we do not agree with the Augsburg paper, which finds the 'reality' of communist ideas not in Plato but in some obscure acquaintance who, not without some merit in some branches of scientific research, gave up the entire fortune that was at his disposal at the time and polished his confederates' dishes and boots, according to the will of Father Enfantin. We are firmly convinced that it is not the practical Attempt, but rather the theoretical application of communist ideas, that constitutes the real danger; for practical attempts, even those on a large scale, can be answered with cannon as soon as they become dangerous, but ideas, which conquer our intelligence, which overcome the outlook that reason has riveted to our conscience, are chains from which we cannot tear ourselves away without tearing our hearts; they are demons that man can overcome only by submitting to them."
Karl Marx, "[Communism and the Augsburg Allgemeine Zeitung]," Rheinische Zeitung, 16 October 1842, just five years before the composition of the Communist manifesto. Trans. Original here. "The Rhineland News, Marx argued, would not concede communism any 'theoretical reality,' much less any effort at 'practical realization.' He found the theory much more ominous than the practice. The 'intellectual implementation' of communist ideas would be the 'genuine danger,' for such ideas could 'defeat our intelligence, conquer our sentiments. . . ." To meet that danger, he proposed a careful study of the works of prominent communists, for the purpose of engaging in a 'fundamental criticism of their ideas.' By contrast, 'practical attempts [to introduce communism], even attempts en masse, can be answered with cannons'" (Jonathan Sperber, Karl Marx: a nineteenth-century life (New York: Liveright Publishing Company, 2013 ), 99, on a tip from John Gray, "The real Karl Marx," The New York review of books 60, no. 8 (May 9, 2013): 38 (38-40)).
What is more, "In a speech to the Cologne Democratic Society in August 1848, Marx rejected revolutionary dictatorship by a single class as 'nonsense'—an opinion so strikingly at odds with the views Marx had expressed only six months earlier in the Communist Manifesto that later Marxist-Leninist editors of his speeches mistakenly refused to accept its authenticity—and over twenty years later, at the outbreak of the Franco-Prussian War, Marx also dismissed any notion of a Paris Commune as 'nonsense'" (Gray, 38).