The Concept of Anxiety
The Concept of Anxiety (): "A Simple Psychologically Orienting Deliberation on the Dogmatic Issue of Hereditary Sin", is a philosophical work written by Danish philosopher Søren Kierkegaard in 1844. The original 1944 English translation by Walter Lowrie (now out of print), had the title The Concept of Dread. "The Concept of Anxiety" was dedicated "to the late professor Poul Martin Møller". He used the pseudonym Vigilius Haufniensis (which, according to Kierkegaard scholar Josiah Thompson, is the Latin transcription for "the Watchman" of Copenhagen) for "The Concept of Anxiety".
On Certainty
On Certainty (, original spelling ) is a philosophical book composed from notes written by Ludwig Wittgenstein over four separate periods in the eighteen months before his death on 29 April 1951. He left his initial notes at the home of Elizabeth Anscombe, who linked them by theme with later passages in Wittgenstein's personal notebooks and (with G. H. von Wright), compiled them into a German/English parallel text book published in 1969. The translators were Denis Paul and Anscombe herself. (The editors also numbered and grouped the 676 passages; citations to the work are standardly given as OC1..OC676 rather than by page number.)