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. ↗
Special emphasis should be laid on this intimate interrelation of general statements about empirical fact with the logical elements and structure of theoretical systems. ↗
Thus, in general, in the first instance, the direction of interest in empirical fact will be canalised by the logical structure of the theoretical system. ↗
Truly it is an evil to be full of faults; but it is a still greater evil to be full of them and to be unwilling to recognize them, since that is to add the further fault of a voluntary illusion. ↗