In the eighth and last paragraph of Lumen gentiums first chapter, "The Mystery of the Church," attention shifts to ask where the Church that was given its basic and central theological description in the first seven paragraph is to be found. Before providing the Catholic answer to that question, the Council made an important point, one which I think sets out the fundamental challenge of ecclesiology. It presents, as if in parallel columns, distinct dimensions of the Church, as here:community of faith, hope & love // visible structuremystical Body of Christ // hierarchical societyspiritual community // visible assemblyendowed with heavenly gifts // earthlyholy // always needing to be purifiedThe Council insisted that these sets of characteristics do not describe two realities, two Churches, but a single reality, a single Church, that is comprised of a divine and a human element. It then cautiously offered "a not middling analogy" with the mystery of the Incarnation. As in christology, however, there is a great temptation not only to distinguish but to separate these elements of an integral ecclesiology. One sees it when an opposition is stated or implied between conceiving or imagining the Church as mystery or communion and as People of God, or when Avery Dulles five ways of thinking about the Church are hardened into five ways of being the Church, or when people speak of "the institutional Church" as if it were something apart from them or apart from the spiritual communion.Five decades ago, James Gustafson published a little book Treasure in Earthen Vessels: The Church as a Human Community. He aimed it at what he thought was a common tendency in Protestant ecclesiology that he described as "theological reductionism," that is, "the exclusive use of Biblical and doctrinal language in the interpretation of the Church," this done, on "the explicit or tacit assumption that the Church is so absolutely unique in character that it can be understood only in its own private language." Gustafson offered an analysis of the Church as a human, natural, political community, a community of language, interpretation, memory and understanding, belief and action. Throughout he made use of a method that instead of beginning with what is unique and transcendent about the Church begins with what it has in common with other human communities in order to discover what is unique about it.Gustafson once told me that some Protestants reacted by wondering if he was about to become a Roman Catholic. Catholic ecclesiology at the time, after all, so concentrated on the human aspects of the Church, particularly its institutional character, that the theological aspects were largely neglected. I sometimes think that since Vatican II Catholics have so emphasized the theological elements as to be in danger of falling into the theological reductionism Gustafson was trying to counter. In any case, the danger of separating the unique and transcendent elements from the common and quite human elements continues to exist.