Perhaps, Raju Balsekhar (Refer: Advaita, Buddha and the Unbroken
Whole, Zen Publications, Mumbai) has read in detail about both
Ramana and Nisargadutta Maharaj. He kept a picture of Bhagavan,
in his study above his desk. He says that both are realized souls and
guides for humanity. What I feel is that Bhagavan realized the Self,
and then came to Arunachala to practise "tapas" for the sake of
devotees and heard and read, and wrote books, again for the sake of devotees. In the case of Nisarga Dutta Maharaj, it was the usual order
reading, tapas and realization.