Sam Hamstra Jr. is the Affiliate Professor of Church History and Worship at Northern Seminary. He is the editor of several studies, most recently The Reformed Pastor: Lectures on Pastoral Theology by John Williamson Nevin, and has authored several works on worship, including What's Love Got to Do With It? How the Heart of God Shapes Worship. John Williamson Nevin (1803-1886), was a professor successively at Western Theological Seminary, the Theological Seminary of the German Reformed Church at Mercersburg, and Franklin and Marshall College. He was a leading nineteenth-century theologian and founding editor of Mercersburg Review.