Christian Unity

This term, one of my tutors and I attended an ecumenical event in London in which we were invited to encounter the musical cultures of various apostolic denominations. It was a fascinating evening, in which we Latins contributed some Byrd and some plainchant. Today I listened to a lecture online given by Metropolitan Kallistos Ware, an alumnus of this University, in which he discussed the possibilities in the future of Orthodox-Roman relations. Most interesting, particularly the breakdown of authority into three tiers: local, regional and universal. It strikes me that the organizational structure of the Church might not be  of divine command, but might be venerable tradition. I'm not sure, it's something I'll need to think about. When God mentions the seven Churches in Revelation, for instance, he's not so much instituting patriarchates, but describing the existing situation in order to aid the spread of His Word. I haven't seen any more of Metropolian Kallistos's work, but this has been very thought provoking for me.