Kierkegaard's first major work, published under pseudonyms, presents two modes of existence: the aesthetic (pleasure-seeking, ironic, detached) and the ethical (committed, responsible, choosing). The first volume contains the famous 'Diary of a Seducer'; the second consists of long letters from a judge urging the aesthete to marry. Neither author is Kierkegaard; both are masks through which he stages the fundamental choice facing every human being. The book invented a new way of doing philosophy, through personality rather than argument. Existentialism begins here.