In Advaita Vedanta and Jnana Yoga Nididhyasana (Sanskrit: निदिध्यासन) is profound and repeated meditation on the mahavakyas, great Upanishadic statements such as "That art Thou", to realize the identity of Atman and Brahman. It is the fourth step in the training of a sisya (disciple), consisting of preparatory practices, listening to the teachings as contained in the sruti, reflection on the teachings, and nididhyasana.
Nididhyasana is the final step in the correct understanding of the meaning of the Mahavakyas. Classical Advaita Vedanta emphasises the path of Jnana Yoga, a progression of study and training to attain moksha. It consists of four stages:[web 1]
Sankara explains Nididhyasana as meditation with determination. Sankara states:-
According to Suresvara, Nididhyasana is the culmination of the practice of sravana and manana, which is an indirect intuition of Brahman and does not mean meditation but knowledge (vijnana) i.e. understanding the meaning of the Sruti on the basis of vacya-vacaka relation underlying the mahavakya. Suresvara states:-
Nididhyasana consists in acquisition of vakyarthajnana and this verse explains the purport of sunisnata.
According to Vacaspati, sravana, manana and nidihyasana are a chain of causes contributory to the knowledge of the oneness of Brahman. The Vivarna school considers sravana as the principal cause but Suresvara treats sravana and manana to be co-existent, these two culminate into nididhyasana.
According to Madhva the knowledge acquired by study ('sravana') and stabilized by reflection ('manana') is made the basis of steady contemplation ('nididhyasana'); these are the three stages of inquiry that take the form of Dhyana. Radhakrishnan has defined Nididhyasana as "the process by which intellectual conscience is transformed into a vital one there is stillness, a calm in which the soul lays itself open to the Divine".