The Concept of Anxiety
All of Kierkegaard's books have either a preface, dedication, or prayer at the beginning. This book includes a lengthy introduction. "The Concept of Anxiety" was published on exactly the same date as "Prefaces", June 17, 1844. Both books deal with Hegel’s idea of mediation. Mediation is a common thread throughout Kierkegaard’s works. His work up to this point was to show that faith was being mediated by knowledge. Here he takes up the questions of sin and guilt.
Darwin's Dangerous Idea
Dennett's previous book was "Consciousness Explained" (1991). Dennett noted discomfort with Darwinism among not only lay people but also even academics and decided it was time to write a book dealing with the subject. "Darwin's Dangerous Idea" is not meant to be a work of science, but rather an interdisciplinary book; Dennett admits that he does not understand all of the scientific details himself. He goes into a moderate level of detail, but leaves it for the reader to go into greater depth if desired, providing references to this end.