Sentence:  Briefly it may be stated: Operations come first; concepts follow; theory  aims at developing concepts, from operations, plus a nomological network for those concepts, which explains the structure of the data obtained through those operations. And this does not exclude the theorist from doing some <WSD>'armchairing</WSD>' in thinking about logically consistent models, their empirical pentialities, their assumptions and their implications; he may, and usually will, venture some possible empirical interpretations of a model, but in doing so he will carefully avoid any substantive (nonformal) pre-operational definition of a concept or construct. 
Meaning of the word marked with <WSD> tags:  To theorize based on analysis of data that was gathered previously; To reflect.