sentence1: But why? She paused a long time, and said at last: "Perhaps ”because I want to be ”free!" And, as she spoke, I had a sudden vision of broad spaces, virgin tracts of forests, untrodden lands ”and a realization of what freedom would mean to such a nature as Mary Cavendish. 
sentence2: Mary Cavendish was a free spirit who wanted to explore open spaces and untouched lands.