Sentence:  At this date , it seems probable that the name of Serge Prokofieff will appear in the archives of History , as an effective Traditionalist , who <WSD>was</WSD> fully aware of the lure and danger of experimentation , and used it as it served his purpose ; yet was never caught up in it - never a slave to its academic dialectics . 
Meaning of the word marked with <WSD> tags:  have the quality of being; (copula, used with an adjective or a predicate noun)