Albert Einstein, 1916, Fifteenth Edition, 1952
Translated by Robert Lawson
Three Rivers Press, 1961
A popularisation book by Einstein himself. No real demonstrations, and the special theory is clearer and more convincing: I am left with a small disappointment in the end. Also, I feel the appendices are indeed filling in blanks afterwards.
Note to the Fifteenth Edition, p vii
Physical objects are not in space, but these objects are spatially extended. In this way, the concept "empty space" loses its meaning.
28 Exact Formulation of the General Principle of Relativity, p 108
All [...] are equivalent for the description of natural phenomena (formulation of the general laws of nature).
"All Gaussian co-ordinate systems are essentially equivalent for the formulation of the general laws of nature."
Appendix five - Relativity and the Problem of Space
The Concept of Space in the General Theory of Relativity, p 172
This theory arose primarily from the endeavour to understand the equality of inertial and gravitational mass.
p 176
There is no such a thing as an empty space, i.e. a space without field. Space-time does not claim existence on its own, but only as a structural quality of the field.