Answer:
the passengers and Twain perceive the river in very different ways.
Explanation:
Right after it, Twain continues: <em>"Now when I had mastered the language of this water and had come to know every trifling feature that bordered the great river as familiarly as I knew the letters of the alphabet, I had made a valuable acquisition."</em>
He sees the river in a different way and much is to be told from what the river shows, it seems, but passengers are not able to see what he sees because they do not share the same knowledge.
