What does Twain mean when he says "the romance and the beauty were all gone from the river"? Show another instance.in Life on the Mississippi
By the time of your quote, learning-to-be-a-steamboat-pilot Twain has realized that he has lost his romanticized vision of what becoming a pilot means. Before starting that process, Twain had imagined that there would be fine adventures and great prestige in piloting one of the great Mississippi steamboats. He had not realized the tremendous amount of work and learning that he was undertaking when he became Bixby's pupil, and he could not know that the learning process would destroy the appreciation of the river's beauty that had been part of the original attraction.
All the value any feature of it (the river) had for me now was the amount of usefulness it could furnish toward compassing the safe piloting of a steamboat.