Opening paragraphs.........................

     It is sometimes said that existentialism is more of a mood than a philosophy, and that it can be traced back to anguished novelists of the nineteenth century, and beyond that to Blaise Pascal, who was terrified by the silence of infinite spaces, and beyond that to the soul-searching St. Augustine, and beyond that to the Old Testament's weary Ecclesiastes and to Job, the man who dared to question the game God was playing with him and was intimidated into submission.  To anyone, in short, who has ever felt disgruntled, rebellious, or alienated about anything.
     But one can go the other way, and narrow the birth of modern existentialism down to a moment near the turn of 1932-3, when three young philosophers were sitting in the Bec-de-Gaz bar on the rue du Montparnasse in Paris, catching up on gossip and drinking the house speciality, apricot cocktails.

-Sarah Bakewell,  At The Existentialist Café:  Freedom, Being, and Apricot Cocktails