The realism-driven Nyaya school of Hinduism denied that either the world (Prakrti) or the soul (Purusa) are an illusion. Naiyayikas developed theories of illusion, typically using the term "Mithya", and stated that illusion is simply flawed cognition, incomplete cognition or the absence of cognition. There is no deception in the reality of Prakrti or "Pradhana" (creative principle of matter/nature) or Purusa, only confusion or lack of comprehension or lack of cognitive effort, according to Nyaya scholars. To them, illusion has a cause, that rules of reason and proper "Pramanas" (epistemology) can uncover.