One of the most significant moments in my Physics education came during my sophomore year in college. I decided to pick up a copy of "Mechanics" by Landau and Lifshitz that was on reserve in the library for the mechanics class that I was taking. This is the first volume in the internationally renowned series of textbooks on theoretical Physics, the series that has a reputation for its sparse and difficult writing style, as well as the undoubted difficulty and brilliance of the material presented. This is probably the reason why until that point I didn't even bother looking at these books, but for whatever reason that fateful night I decided to take a look at this particular volume. To my surprise, the book was actually pretty readable and the first few chapters revealed an entirely new way of looking at Physics. Until that point I was used to thinking about Physics as a set of laws and equations, relatively succinct but otherwise somewhat arbitrary and ad-hoc. Landau and Lifshitz's book started from a very different point; it gave some deep underlying principles as a starting point behind the development of physical laws and equations. Based on that I had a new and deeper appreciation of my chosen field of study, and I gained a whole new way of looking at the physical reality.
Granted, the book is really not a walk in the park. Many later chapters can be rather technically demanding, and a prior course on theoretical mechanics at college level is probably the minimal level of preparation that can get a reader through the whole text. There aren't all that many examples that are thoroughly worked out, but all of the problems are given (rather concise) solutions - you still need to fill in some of the more important steps on your own. Mechanics is not an area of active modern research, so this is not necessarily a book that will help one with their scientific careers. However, it provides a solid grounding in some of the most basic physical concepts, and the skills and techniques acquired here can be very important in other areas of Physics. All said, this is a classic textbook that anyone who is serious about a career in Physics would be well advised to go through.
