Sentence:  Lucretius has remarked : `` The reason why all Mortals are so gripped by <WSD>fear</WSD> is that they see all sorts of things happening in the earth and sky with no discernable cause , and these they attribute to the will of God '' . 
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)