The Buddhist text, Abhidharmakosa of Vasubandhu also says virtually the same thing! http://abhidharmakosha.blogspot.com/ http://en.wikipedia.org/wiki/Abhidharmakosha Among the books which explain this scripture are: 1) Sukomal Chaudhuri's Analytical Study of Abhidharmakosa 2) Louis De La Vallee Poussin's Abhidharmakoshabhasyam In the Abhidharmakosa, Akash(Ether) is not considered as a Dhatu. Chapter 1 describes the other four as primary Dhatus and these are referred to as Forces (rather than Matter). These four combine to create other states of derived Matter. 1) Earth provides Supporting Force (Fermion) 2) Water provides Cohesion Force (Boson) 3) Fire provides Ripening Force (Radioactive Decay) 4) Air provides Expanding Force (Diffusion) Note that Vasubandhu differs from Sankya because he exchanged the functions for Water and Air.