 John’s naturalistic conception of cooperative association informs the famous organic analogy that he proposes and develops in the Policraticus. Ascribing his insight to a letter of instruction (John’s creation) purportedly by Plutarch to Emperor Trajan, John commences with the simple observation that the commonwealth may be likened to a “body which is animated” (PC: 66; on the history of the controversy about the letter’s authenticity, see Martin 1984: 194–96). The different offices of political society are represented as analogous to the distinct parts of the human anatomy. Like all bodies, the commonwealth is guided by a soul, which John assigns to “those who direct the practice of religion” (PC: 67). Yet, just as the eternal human soul is not coextensive with the mortal physical organism within which it resides, the clerical soul of the polity is not, strictly speaking, a member of the commonwealth (see Nederman 2013). Because the political creature is an essentially secular entity, the body politic is ruled by the prince, who “occupies the place of the head” (PC: 69). (For further discussion of the relationship between the secular body and its ecclesiastical soul, see the supplement on  Princely Tyranny and the Liberty of the Church.)