Centuries later, the 5th century CE Nyaya school scholar Prastapada revisited the premise of Ishvara. He was followed by Udayana, who in his text "Nyayakusumanjali", interpreted "it" in verse 4.1.21 of Nyaya Sutra above, as "human action" and "him" as "Ishvara", then he developed counter arguments to prove the existence of Ishvara. In developing his arguments, he inherently defined "Ishvara" as efficient cause, omnipotent, omniscient, infallible, giver of gifts, ability and meaning to humanity, divine creator of the world as well as the moral principles, and the unseen power that makes the karma doctrine work.