tamah-pradhanas tv abhavad
mahatah-of the mahat-tattva; tu-but; vikurvanat-being transformed; rajah-material mode of passion; sattva-mode of goodness; upabrmhitat-because of being increased; tamah-the mode of darkness; pradhanah-being prominent; tu-but; abhavat-took place; dravya-matter; jnana-material knowledge; kriya-atmakah-predominantly material activities.