This book provides a concise overview of Marxs philosophy and political economy, tracing various changes of his theoretical views over time through his practical and theoretical engagements with contradictions of capitalism from the unique perspective of Japanese Marxism. While it offers an objective introduction to Marxs critique of capitalism, Sasaki uniquely pays particular attention to the concept of metabolism, whose disruption under the capitalist mode of production causes exhaustion of labour-power as well as natural resources. Sasaki reconstructs Marx as a revolutionary thinker, whose devoted his entire life for the sake of establishing a more free and equal society beyond capitalism. Sasakis book shows that Marxs passion for the socialist revolution in his last years is recorded in his late excerpt notebooks that become available through the Marx-Engels-Gesamtausgabe.