Sentence:  It was safe to assume that Papa , sighing heavily , had said many times to his remaining daughter , `` Thank God your poor mother was spared this '' , and indeed it might be true that it had been easier for Henrietta to leave , with her hand in Charles ' hand , just because her `` poor mother '' was gone already and would never <WSD>know</WSD> . 
Meaning of the word marked with <WSD> tags:  be cognizant or aware of a fact or a specific piece of information; possess knowledge or information about