I graduated with a Ph.D. in Mechanical Engineering in 1988 and quickly entered management; therefore my mathematics have not be extensively exercised for many years.  Having had an affection for physics ever since being a teenager, I am finally at a point in my life where I have the time to do a little self study.  After purchasing over 50 books that touch on relativity, I have found my favorite GR book in T.P. Cheng's masterpiece.  I have used it as my guide to understand tensors, which were completely new to me, and digest and derive the foundational concepts and equations including EP, curved space, curved spacetime, covariant derivatives, parallel transport, Riemannian curvature, general covariance, Einstein's field equation, Schwarzschild's solution, and the famous applications of the theory to the precession of Mercury's orbit and the gravitational deflection of light.  While I have supplemented my study with extra reading from Hartle, Hobson, Wald, Kenyon, Foster, Lawden, Stephani, D'Inverno, Gron, Ohanian, Zee, Kennedy, Alder and Misner, T.P Cheng's book has been my guide throughout.<br><br>With my background, I find Cheng's balance of mathematics and physical insight perfect for my journey through the beauty and complexity of GR.  Cheng's approach to teaching the necessary mathematical tools in parallel to the physics has helped me over the "tensor hurdle" while maintaining my interest to press on.  Books that spend the first chapters only dealing with the math sapped my motivation and give the impression that GR is mathematics, not physics.  In a sense, Cheng's book is how Einstein created the theory - learning the necessary nomenclature and Riemannian geometry to help describe his incredible physical intuition.<br><br>I have worn out my paperback version, including many notes-to-self in the margins.  Therefore, while I will always keep and cherish this ruffled version, I have just purchased a new hardback version to every now and then admire in unadulterated form this gem of physics education.