You know Dover-- wonderful for reprinting very high quality texts from back in the 60's or earlier, for 10 bucks US or less, and perfectly adequate for topics that haven't changed since Euclid. But "some" topics, especially those subject to numerical methods, combinatorics and computing, need a makeover to include the web, NumPy, MatLab (or GNU Octave free) and tablet sized supercomputers vs. those era's ideas of computing and combinatorics.This wonderful book gives us the best of both worlds, as the author has graciously updated many areas, such as Russell's paradox (even though it goes back to 1901, let alone 1971!) with additional current set theory paradoxes and current thinking, and many other aspects of set theory and mathematical logic that have become crucial to newer topics like AI, natural language processing, computing, linguistics, combinatorics, the competing category theories, and much more.Even VERY current topics like equivalence in string and M theory use foundation concepts from set theory, so the topic itself is seminal and useful for many fields, from programming to engineering. The book is extremely well written, and quite intuitive (and even fun!) given the dry topic. Although every time I opine that a book requires fairly advanced undergrad I get a bunch of nasty emails from AP High School folks saying they get it, nevertheless, I have to be honest with potential buyers that this IS BOTH a basic (at first), then very advanced text as you proceed. For autodidacts, home schoolers, etc. it makes a wonderful adjunct to the more current texts, as it builds much more gently and intuitively than the majority of "show off" texts today, that expect much more from the reader notation wise.Every author and publisher willing to give as generous a "look inside" as this book does deserves our respect, so do take advantage of it if you're concerned about the level. When you do, you'll see the plentiful diagrams and examples/ exercises that have made this author so popular, for so many decades.If you're old like me, you might "twinge" at the thought of this book, the foundations of which began what was called (and what we were "subjected to") known back then as the "new math." Sets became the transitional pain we endured. Here's the ideal way to make peace with that issue at under 15 bucks! In fact, the author, even back in 71 at the height of it, points out how set theory, in historical perspective, isn't "new" at all, but truly foundational, and as we go forward into topology, rings and even tensors, set theory keeps right up. And if you have a taste for the philosophy of math, indeterminacy, incompleteness, Frege, Godel, uncertainty, and those areas, this is a MUST. Luckily, set theory's "Heisenberg" (Paul Joseph Cohen) published right in this book's wheelhouse, so you'll miss very little by making this choice in that regard. Enjoy!