Complex sentence: Eventually, the lack of outside musical stimuli dulled the young midshipman's hunger to learn, and he wrote to Balakirev that after two years at sea he had neglected his musical lessons for months.
Split into simpler sentences: Eventually, the lack of outside musical stimuli dulled the young midshipman's hunger to learn. He wrote to Balakirev that after two years at sea he had neglected his musical lessons for months.