Althusser (2005), p. 59: "Ultimately, as this procedure enables us to find materialist elements in all Marx's early texts, including even the letter to his father in which he refuses to separate the ideal from the real, it is very difficult to decide when Marx can be regarded as materialist, or rather, when he could not have been!" Althusser, Louis (2005) [1965]. For Marx. Translated by Brewster, Ben. London: Verso Books. ISBN978-1-84467-052-9.