This is a truly 'modern' theoretical physics book, well written, and full of wisdom. It contains may ideas and viewpoints that are not generally known; for example, the fact that force is naturally a 1-form, and the geometric meaning of the canonical momenta of Hamiltonian mechanics. Introductory physics textbooks have a long way to catch up with how modern physicists think, and this is one of those books that does things right. The book treats special relativity, general relativity, cosmology and also the mathematics of the calculus on manifolds. I know of no better place to really understand what tangent vectors and 1-forms are, and the basic ideas of tensors and the the concept of a smooth manifold. It teaches one to think correctly about concepts which are not treated correctly by older books. One can gain a good facility with calculus on manifolds by working through this book.