The "Pure Theory of Law" is generally considered among the most original contributions made by Hans Kelsen to legal theory. His book with that title was first published in 1934, and in a greatly expanded second edition (effectively a "magnum opus" doubled in length of presentation) in 1960. The second edition appeared in English translation in 1967, as "Pure Theory of Law"; However, the original terminology which was introduced in the first edition was already present in many of Kelsen's writings from the 1920s, and was also subject to discussion in the critical press of that decade. Although the second edition is so much longer, the two editions have a great deal of similar content.