Gerald Christianson is Emeritus Professor in Residence at Gettysburg Lutheran Seminary in Gettysburg, Pennsylvania, where he has taught early and medieval church history since 1967. Among his recent works, he is the co-author or co-editor of The Spirituality of the German Awakening, a volume in the series Classics of Western Spirituality (2003); Introducing Nicholas of Cusa: A Guide to a Renaissance Man (2004); Reject Aeneas, Accept Pius: Selected Letters of Aeneas Sylvius Piccolomini (Pope Pius II) (2006); and the forthcoming The Church, the Councils, and Reform: The Legacy of the Fifteenth Century (2008).