Sentence:  Yet often <WSD>fear</WSD> persists because , even with the most rigid ritual , one is never quite free from the uneasy feeling that one might make some mistake or that in every previous execution one had been unaware of the really decisive act . 
Meaning of the word marked with <WSD> tags:  an emotion experienced in anticipation of some specific pain or danger (usually accompanied by a desire to flee or fight)