Hobbes made his name as the author of a brief book about citizenly duty published in 1642. In its various editions, De cive brought his ideas about the need for undivided sovereignty to a wide, and mostly admiring, Continental audience. Similar ideas in an earlier, unpublished, but well-circulated treatise of Hobbes's came to the notice of men of political influence in England in 1640, so that he was known, in parliamentary circles at least, as a political thinker some years before any of his work had gone into print. It is as a political theorist that he is still studied today. Hobbes's Leviathan has eclipsed De cive as the official statement of his theory, but it has much in common with the book he published in 1642 and the manuscript that he circulated in 1640. It is Hobbes's political doctrine that continues to get attention, and new editions of Leviathan are still being issued.