I've selected Barth's Protestant Theology in the Nineteenth Century for this week's Friday's Finds. It's a theological history book about the liberal protestant theologians from 1700-1900 written by an expert of this era including the most influential liberal Protestant theologians of the Enlightenment: Rousseau, Lessing, Kant, Herder, Novalis, Hegel, Schleiermacher, Wegscheider, De Wette, Marheineke, Baur, Tholuck, Menken, Feuerbach, Strauss, Schweizer, Dorner, Muller, Rothe, Hofmann, Beck, Vilmar, Kohlbrugge, Blumhardt, and Ritschl (all with dedicated chapters). And many others appear throughout without explicit chapters, most notably Kierkegaard, Goethe, Louis XIV, and others. This isn't a history of all Protestant theologians, but those in the long chain of Pietism and the Enlightenment.
It's impossible to understand Karl Barth without understanding Friedrich Schleiermacher, and this book is an excellent read and very accessible introduction to the background of the 18th and 19th centuries, and sets the trajectory for the theological problems of the 20th and 21st centuries.
Anyone interested in theology and theological history should have this book on your shelf.