Sri Chaitanya Mahaprabhu showed by his personal life the validity of the doctrines of devotion described in Srimad Bhagavata. Holding Achintya-Bheda-bheda or identity-in-difference to be the nature of the Ultimate Reality whom he called Sri Krishna, Chaitanya demonstrated how Bhakti is the sure way to higher spiritual development.
The great secret of true success, of true happiness, is this: the man or woman who asks for no return, the perfectly unselfish person, is the most successful.
-Swami Vivekananda