Ramkrishna Bhattacharya analyzes Debiprasad Chattopadhyaya’s evolving perspective on early Buddhism and the five contemporary heretical sects in the Sāmañña-phala-sutta. Moving from a rigid, doctrinal framework in Lokāyata to a concrete historical-materialist method in later works, Chattopadhyaya re-examined ancient Indian materialism and radical social critique within its specific historical epoch.