Complex sentence: He was the founder of Western Marxism, the interpretive tradition that departed from the Marxist ideologic orthodoxy of the USSR; as such, he developed the theory of reification, and contributed to Marxist theory with developments of the class consciousness theory by Karl Marx.
Split into simpler sentences: He was the founder of Western Marxism, the interpretive tradition that departed from the Marxist ideologic orthodoxy of the USSR. He developed the theory of reification, and contributed to Marxist theory with developments of the class consciousness theory by Karl Marx.