Periodicals of the latter half of the seventeenth century were usually characterized by two traits: first, their authors were generally not professional writers but amateurs who took up their pens for a cause; and, second, when the cause no longer proved of political, religious or social consequence, the periodical was discontinued. Politics and religion generated the most late seventeenth-century periodicals; scholarly and scientific interests prompted the next largest category. Whereas the seventeenth-century periodical had primarily been produced by amateurs, the eighteenth-century periodical was largely written and conducted by what would later be called the 'professional' writer. Samuel Johnson produced biographies and parliamentary reports for the Gentleman's Magazine in the late 1730s, later turning out the twice-weekly essay sheet the Rambler and contributing regular essays to the Adventurer and the Universal Chronicle. The modern magazine had its origin in periodicals comprising materials so various that the early eighteenth century referred to them as 'miscellanies'.