Four years ago, I read a book on the history of mathematics up to 1970 or so. It was very interesting up until the end. The last few chapters, though, were on lattices. The author claimed that lattices were taking math by storm, and that soon lattices would be one of the central objects in mathematics, and many other such claims similar to those now made in reference to category theory. I couldn't find the book online, but I found references to similar ideas in this post:http://mathoverflow.net/questions/14341/good-lattice-theory-books Question 1: Was lattice theory central to mid-twentieth century mathematics? Question 2: Is it central now?