 Kant’s basic idea can be grasped intuitively by analogy with the idea of political freedom as autonomy (See Reath 1994). Consider how political freedom in liberal theories is thought to be related to legitimate political authority: A state is free when its citizens are bound only by laws in some sense of their own making — created and put into effect, say, by vote or by elected representatives. The laws of that state then express the will of the citizens who are bound by them. The idea, then, is that the source of legitimate political authority is not external to its citizens, but internal to them, internal to “the will of the people.” It is because the body politic created and enacted these laws for itself that it can be bound by them. An autonomous state is thus one in which the authority of its laws is in the will of the people in that state, rather than in the will of a people external to that state, as when one state imposes laws on another during occupation or colonization. In the latter case, the laws have no legitimate authority over those citizens. In a similar fashion, we may think of a person as free when bound only by her own will and not by the will of another. Her actions then express her own will and not the will of someone or something else. The authority of the principles binding her will is then also not external to her will. It comes from the fact that she willed them. So autonomy, when applied to an individual, ensures that the source of the authority of the principles that bind her is in her own will. Kant’s view can be seen as the view that the moral law is just such a principle. Hence, the “moral legitimacy” of the CI is grounded in its being an expression of each person’s own rational will. It is because each person’s own reason is the legislator and executor of the moral law that it is authoritative for her. (For a contrasting interpretation of autonomy that emphasizes the intrinsic value of freedom of choice and the instrumental role of reason in preserving that value, see Guyer 2007).