Sentence:  Mythological concepts may by all means still be used , but they can be <WSD>used</WSD> responsibly only as `` symbols '' or `` ciphers '' , that is , only if they are also constantly interpreted in non mythological ( or existential ) terms . 
Meaning of the word marked with <WSD> tags:  put into service; make work or employ for a particular purpose or for its inherent or natural purpose