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.
In youth the days are short and the years are long. In old age the years are short and day's long.
No more war! Never again war! If you wish to be brothers drop your weapons.
The two most misused words in the entire English vocabulary are love and...