In deriving the Euler-Lagrange equations from the Principle of Least Action, most mechanics textbooks have a clear and complete argument, which I can follow step-by-step, but which always leaves me with a feeling of unease. In particular, there is a point in the derivation involving integration-by-parts and, right there, my qualitative understanding fails. From then on, it is an unsatisfying mathematics exercise, rather than a clear physical argument. In their short, entertaining book, The Theoretical Minimum, Leonard Susskind and George Hrabovsky present a derivation I've never seen before—one that is more direct and, for me, much more satisfying. This alone is worth the price of the book.
This little book is a terse, but fairly complete review of non-relativistic classical mechanics. It is advertised to be the first of a series of short texts about theoretical physics. The later books, it is claimed, will carry the reader up through...
