| − | [[Einstein]] asserted in his book ''The meaning of Relativity'' (1922) that according to his conviction the possibility of explaining the numerical equality of [[inertia]] and [[gravitation]] by the unity of their nature is a sufficient reason for holding [[General Theory of Relativity]] as superior over the conceptions of classical theories and for considering all the difficulties encountered when making a way for his new theory "as small" in this respect.<ref>{{cite book |author=Marco M. Capria, Aubert Daigneaut et al. |title=Physics Before and After Einstein |publisher=IOS Press |year=2005 |chapter=5. General Relativity: Gravitation as Geometry and the Machian Programme |isbn=1-58603-462-6 |url= | + | [[Einstein]] asserted in his book ''The meaning of Relativity'' (1922) that according to his conviction the possibility of explaining the numerical equality of [[inertia]] and [[gravitation]] by the unity of their nature is a sufficient reason for holding [[General Theory of Relativity]] as superior over the conceptions of classical theories and for considering all the difficulties encountered when making a way for his new theory "as small" in this respect.<ref name="Capria">{{cite book |author=Marco M. Capria, Aubert Daigneaut et al. |title=Physics Before and After Einstein |publisher=IOS Press |year=2005 |chapter=5. General Relativity: Gravitation as Geometry and the Machian Programme |pages=97, 114|isbn=1-58603-462-6 |url= |
| | |quote=The importance of the asserted identity of the two masses was stressed by Einstein in unambiguous terms: ''The possibility of explaining the numerical equality of inertia and gravitation by the unity of their nature gives to the general theory of relativity, according to my conviction, such a superiority over the conceptions of classical mechanics, that all the difficulties encountered must be considered as small in comparison with this progress.''}}</ref>{{#tag:ref|cf. ''Dirac once said, "That which is not observable does not exist," but these days what is said is, "I know my theory is right. Therefore anything required to make it work must also be right whether observable or not."''<ref name="DismantlingBB">{{cite book|author=Alex Williams, John Hartnett|title=Dismantling the Big Bang|publisher=Master Books|location=Green Forest, AR, USA|year=2005|pages=288|isbn=978-0-89051-437-5 |url=http://books.google.com/books?id=EvN9Gfbox74C&printsec=frontcover&dq=dismantling+the+big+bang&hl=sk&sa=X&ei=uE2VUtadEYrMygOThYDABQ&redir_esc=y#v=onepage&q=Dirac&f=false}}</ref>|group=note}} | | |quote=The importance of the asserted identity of the two masses was stressed by Einstein in unambiguous terms: ''The possibility of explaining the numerical equality of inertia and gravitation by the unity of their nature gives to the general theory of relativity, according to my conviction, such a superiority over the conceptions of classical mechanics, that all the difficulties encountered must be considered as small in comparison with this progress.''}}</ref>{{#tag:ref|cf. ''Dirac once said, "That which is not observable does not exist," but these days what is said is, "I know my theory is right. Therefore anything required to make it work must also be right whether observable or not."''<ref name="DismantlingBB">{{cite book|author=Alex Williams, John Hartnett|title=Dismantling the Big Bang|publisher=Master Books|location=Green Forest, AR, USA|year=2005|pages=288|isbn=978-0-89051-437-5 |url=http://books.google.com/books?id=EvN9Gfbox74C&printsec=frontcover&dq=dismantling+the+big+bang&hl=sk&sa=X&ei=uE2VUtadEYrMygOThYDABQ&redir_esc=y#v=onepage&q=Dirac&f=false}}</ref>|group=note}} |