: It cannot be denied that this quote is far more specific than the one from The Holy Family. It also cannot be credibly said that Lenin 'invented' the idea of the revolutionary vanguard. The more familiar an individual becomes with Lenin's work, the more apparent it becomes how Lenin merely applied the writings of Marx---and, in particular, Engels---to the conditions of the age he lived in.
More particularly, he applied to the Marx of 1848, from which some works were circulating, certainly, that was where trotsky picked up the idea of 'permenant revolution' from. Further, Lenin also was applying his great admiration for the jacobins to teh age he lived in. Certainly, he didn't invent vanguardism, but he was the first to mix the idea of the vanguard with Marxism.
Engels' quote does not demand a vanguard: it does demand a group of class conscious workers struggling to command understanding and clarify the way ahead 'communist understand the line of march' IIRC the Manifesto.
: One may disregard the content of what Engels said, but to separate his words from Lenin's formation of the Bolshevik Party is to misunderstand Lenin's assiduous attention to Marxist theory.
But not to neglect the assidious attention played by such as Rosa Luxemburg or Anton Pannekoek to said marxian theory. Plus, by a simple method of observational science, we can see how the theory of the vanguard has failed in practise, so we are bound to abandon it - but its abandonment does not demand the abandoment of Marxism.
: The idea that Marxist revolution shall spontaneously arise from the atomized members of the working class---or the trade unions---is sheer bunk. A vanguard is necessary to lead the revolution. To repudiate the idea of a revolutionary party is to repudiate the idea of revolution.
Sponteneism is as incorrect as vanguardism, the working-class must come to consciousness, and that does require the work of socialists (who are themselves, it must be remembered, workers) to show the direction of struggle. Discussing the Paris Commune, Marx observes how though many of its prominent player were IWMA members, it was not an IWMA uprising. The conscious revolutionaries were the most prepared to play their part: but revolution, full revolution, requires many times more conscious revolutionaries, it requires a conscious and revolutionary working class, that deliberately sets forward to revolution: "the movement of the immense majority in the interests of teh immense majority" IIRC.
It would be worth noting that the British Socialist Workers Party has roughly 10,000 members (making them the current biggest leftist movement). On a scale with Russia, proportionately, thats the same size as the Bolsheviks. Imagine a revolution led by that tiny band. they scare me - they'd have to shoot me ;)