A couple of non-RPW friends have inquired about the Biblical support for the Regulative Principle within the Church, and especially on where the idea of Circumstances vs. Elements is supported via Scripture. This is one of those questions I've really struggled to chew on and figure out, since I believe the RPW to be Biblically sound and supported, from reading confessional statements of doctrine about it vs. NPW confessional statements, but my own coherent Scriptural knowledge on worship isn't up to snuff at this point to address these issues well. And also, I've heard Gospel Worship by Burroughs is a good resource. What else should I look into for a very basic intro to this sphere of theology. The only other book on worship I've read of any substance is D.G. Hart's Recovering Mother Kirk, which I really like for its history and liturgical Reformed arguments, but that doesn't seem to hit the issue on its head.