It is probably safe to say that all the changes of factual knowledge which have led to the relativity theory, resulting in a very great theoretical development, are completely trivial from any point of view except their relevance to the structure of a theoretical system.

The hypothesis may be put forward, to be tested by the s subsequent investigation, that this development has been in large part a matter of the reciprocal interaction of new factual insights and knowledge on the one hand with changes in the theoretical system on the other.

It is that of increasing knowledge of empirical fact, intimately combined with changing interpretations of this body of fact - hence changing general statements about it - and, not least, a changing a structure of the theoretical system.

From our point of view, better safe than sorry.

Nothing's beautiful from every point of view.

An outsider's point of view is always handy.