Sentence:  Indeed we should say , on the contrary , that the accident of our later discovery made no difference whatever to the badness of the animal 's pain , that it would have been every whit as bad whether a chance <WSD>passer-by</WSD> happened later to discover the body and feel repugnance or not . 
Meaning of the word marked with <WSD> tags:  a person who passes by casually or by chance