I am a physicist and I cannot analyse its philosophical merits. However, I strongly recommend the physicists to read this book, for it contains very insightful discussions on subtle issues usually absent from standard textbooks. This is not an introduction and for a better appreciation it is important the reader to be acquainted with a previous course in relativity. In the following I will comment some of the pearls which, in my opinion, distinguishes this book. It is well known that Lorentz and Fitzgerald tried to interpret the contraction that nowadays bare their names in terms of fundamental interactions among molecules. Since they also strongly advocate on the behalf of the ether concept, nowadays physicists tend to regard this debates as innocuous and the contraction as a manifestation of space itself. In chapter 5, Harvey Brown shows that the search of an atomistic comprehension of the contraction is independent from the existence of the ether and that Einstein himself saw in it a necessary step towards a complete theory. In this remarkable chapter, it is discussed how Einstein saw his theory as analogous to thermodynamics. Other highlights are the discussion of some unconventional views of the relativity theory (chapter 7) and the discussion in chapter 8, following Lévy-Leblond, that Lorentz covariance does not require that light moves with the invariant velocity c, and therefore that it is in principle possible to construct a consistent relativistic theory with a massive photon. Chapter 9 deals with general relativity and is very enlightening, addressing the fundamental question about the contingency of regard the tensor g as the metric of space-time. It is discussed also the sense in which space-time acts in the matter. To finish, let me add a personal remark. The search for quantum gravity and for a better understand of the physics of black-holes has presented clues that general relativity may not be the last word (for example, the prevision of singularities as proved by Penrose) and may be just an effective theory with outstanding results for length scales far larger than Planck's length. This line of reasoning begs for a thorough study of the foundations of and alternative approaches to relativity. This books offer a valuable aid to this purpose.