 Rawls covers the domain of the political by addressing its sub-domains in sequence. The first sub-domain that he addresses is a self-contained democratic society reproducing itself across generations. Once principles are in place for such a society, Rawls moves to a second sub-domain: a society of nations, of which this democratic society is a member. Rawls suggests (though he does not show) that his sequence of theories could extend to cover further sub-domains, such as human interactions with animals. Universal coverage will have been achieved once this sequence is complete, each sub-domain having received the principles appropriate to it.