Complex sentence: Dr. Orison Swett Marden (1850-1924) was an American inspirational author who expounded upon common-sense principles and virtues that make a well-rounded, successful life.
Split into simpler sentences: Dr. Orison Swett Marden (1850-1924) was an American inspirational author who wrote on success and how to achieve it. His writings discuss common-sense principles and virtues that make a well-rounded, successful life.