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.
Hannah Arendt
Already in this work some of the leitmotifs of her canon were apparent. For instance, she introduced the concept of "" (Natality) as a key condition of human existence and its role in the development of the individual. She made clear, in her revisions to the English translation, through explicit reference, that it was "natality" that she was introducing, and would develop further in "The Human Condition" (1958). Although she did not specifically use the word "Natalität" in the original German version, she explained that the construct of natality was implied in her discussion of new beginnings and man's elation to the Creator as "nova creatura". The centrality of the theme of birth and renewal is apparent in the constant reference to Augustinian thought, and specifically the innovative nature of birth, from this, her first work, to her last, "The Life of the Mind".