In the first half of his essay “Ideology and ideological state apparatus”, Althusser states that “the resistance of the exploited classes can find means and opportunities to express itself there” (99). , by which he means in the Ideological State Apparatuses. In the second half of the essay, Althusser argues that there are places that can be found in the ISA that allow for the expression of the exploited class, but this expression is an illusion since they can only express themselves in terms of subjects. Althusser separates the State Apparatus into two sections, one is the Repressive State Apparatus (RSA) and the other is the Ideological State Apparatus (ISA). The RSA includes aspects such as the military, police and government, while the ISA includes aspects such as education, religion and family. RSA is fundamentally different from ISA for two reasons, the first is that RSA is strictly in the public domain while ISA can exist in both the public and private domain. The second difference is that “the repressive state apparatus functions 'by violence', while the ideological state apparatus functions 'by ideology'” (97). Althusser qualifies this statement by saying that the RSA truly works through both violence and ideology since no apparatus can function alone. Thus, in contrast, ISAs function primarily through ideology and secondarily through violence, although most of this violence is usually internal to the apparatus. Althusser concludes his discussion of the distinction between RSA and ISA by saying that “ideological state apparatuses can be not only the stake, but also the site of class struggle, and often of bitter forms of class struggle” (99). By this Althusser means that it is intrinsically difficult to remove the ISA from the “formal” ruling class since they can maintain their roles for a longer period of time than if they are driven from power in the RSA. This also brings us back to the question at hand; How do the resistances of the exploited classes find means and opportunities to express themselves in the ISA? Opportunities for expression come from ideology. For Althusser, ideology is “conceived as a pure illusion, a pure dream, that is, as nothingness. All his reality is external to him” (108). Althusser differs from Marx on who controls this reality. Marx argues that this illusion is controlled by those in power and is used to control those who are not in power.