Derek Olsen posted a thoughtful essay on Episcopal Cafe earlier this week about the continuing value of a physical edition of the Book of Common Prayer, even as parishes increasingly move toward locally printed worship booklets and as digital technology makes it easier and easier to customize liturgies (in authorized and less authorized ways).

Thinking about Derek’s point that a collectively agreed-upon text almost demands a physical instantiation, I’m reminded of what city planners know about the difference between train lines and bus routes.

In a lot of ways, trains and buses do the same thing. They move people along a predetermined route with certain designated stops along the way. Buses are easier to maintain and more flexible, though; and they use the same road infrastructure that’s already there for cars. In the middle of the 20th century many streetcar lines were replaced by bus routes. In fact, outside my old Seattle apartment on 14th Avenue on Capitol Hill, you can still see the lines in the asphalt where the old streetcar tracks were removed and paved over.

But the very flexibility of buses can also be a downside: because commercial development doesn’t tend to follow bus routes in the same way it does train routes. Why? A bus route can be changed anytime by the decision of a transit authority. But because a train or trolley depends on fixed physical infrastructure that can’t be easily moved, it represents a commitment to that location. Open a coffee shop or drugstore next to a train station and you’re likely to benefit from foot traffic for years to come. Open it next to a bus stop and you could be looking at a very unpleasant surprise next month or next year when the bus line switches to the parallel street two blocks over.

Trains, streetcars, and the like have been making a major comeback in recent years in many cities. (Seattle, of course, is a prime example.) Sometimes these projects are criticized as nostalgic, hipster-friendly, gentrification-fests: and there’s truth to some of that assessment. Slick new trains carry more cachet than the good old buses that are the faithful backbones of most cities’ transport networks. In certain cities I’ve lived in (ahem, Atlanta and Dallas) buses are used in large part by people who can’t afford cars. Meanwhile, the light rail systems in those cities serve major business and shopping destinations and cater to commuters and tourists. The result is a self-fulfilling cycle and a textbook study opportunity for societal racism and classism.

But I digress–because what I want to say about the prayer book has to do not with the complex social dynamics of transport policy but with that much more basic difference: bus routes are moveable; train routes stay put. From a media-format perspective, buses are digital; trains are print. And like a set of physical tracks embedded in the ground, a physical prayer book represents commitment. A digital set of liturgical resources that live online–even if they’re approved by the General Convention–is easy to change. A physical book that lives in every parish isn’t.

We’re a church with a collective polity, especially when it comes to liturgy. I’d argue that this is part of the charism of Anglicanism (and, of course, of other catholic traditions): we make decisions about our worship at a communal level, not an individual level. This doesn’t mean that there’s no room for adaptation, experimentation, customization: quite the opposite. What it means is that we set the parameters for that flexibility together, as a whole church, through the provisions established in the Prayer Book and its authorized supplements. So get out there and experiment! Try new musical styles, new ways of using space, richer ritual embodiment. Heck, try new texts: if it’s not the primary Sunday service, the BCP’s Order for Holy Eucharist allows you to write your own eucharistic prayer or use New Zealand or the Liturgy of St. John Chrysostom or just about anything you want to do. The point is that it’s the fact that we have some collectively-agreed-on parameters that allows creativity to be generative and not chaotic.

To return to the bus/train analogy, train stations make excellent starting and ending points for bus routes. It’s the predictability of the fixed that allows the flexible to flourish.