Complex sentence: Close, constant study of nature prevented him from going mad; however, the war stayed with him, and finally at the urging of his wife, he began to put his thoughts on paper, at last allowing him to put his horrors behind him.
Split into simpler sentences: Close, constant study of nature prevented him from going mad. However, the war stayed with him, and finally at the urging of his wife, he began to put his thoughts on paper, at last allowing him to put his horrors behind him.