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.
Let each one of us pray day and night for the downtrodden millions, who are held fast by poverty, priestcraft, and tyranny. Pray day and night for them. I care more to preach religion to them than to the high and the rich. I am no metaphysician, no philosopher, nay, no saint. But I am poor and I love the poor.
-Swami Vivekananda