Complex sentence: Gramsci was one of the most important Marxist thinkers in the 20th century, and his writings are heavily concerned with the analysis of culture and political leadership; he is notable as a highly original thinker within modern European thought.
Split into simpler sentences: Gramsci was one of the most important Marxist thinkers in the 20th century. His writings are heavily concerned with the analysis of culture and political leadership and he is notable as a highly original thinker within modern European thought.