The origins of Brahma in Buddhism and other Indian religions are uncertain, in part because several related words such as one for metaphysical Ultimate Reality (Brahman), and priest (Brahmin) are found in the Vedic literature. According to KN Jayatilleke, the Rigveda expresses skepticism about major deities such as Indra whether he even exists, as well as whether the universe has any creator and can this ever be known, as evidenced in its eighth and tenth book, particularly in its Nasadiya Sukta.