Sri Caitanya Mahaprabhu, the supreme Lord, accepted Srila Isvara Puri, a pure teacher (guru) in the line of the Brahma Madhva Sampradaya, as His own Spiritual master.
The Lord preached the full-fledged theistic conception given in Srimad-Bhagavatam (Bhagavat-Purana). Srimad Bhagavatam mainly deals with the comparative study of theism and the ontology of Krsna consciousness. It surpasses all other Vedic literatures, even the Puranas. The Brahma-vaivarta Purana and Padma Purana represent the importance of devotion to Krsna through narration and history to some extent, but fall short of the philosophical and ontological standard set by the Mahapurana, Srimad Bhagavatam. Srimad Bhagavatam can satisfy all Vedantic scholars, for it represents Krsna consciousness in its fullest dignity. Srimad Bhagavatam expounds as the highest attainment of theism not consciousness, intelligence, or ontology, but ecstasy, beauty, and harmony — rasa (spiritual taste). In Srimad Bhagavatam, rasa is all-important. It is a unique treatise, for it takes theism from the plane of intellectual jugglery to the domain of rasa.
Srimad Bhagavatam is a vast treatise in the Sanskrit language, filled with essential information, historical reference, and expositions on the major schools of philosophy. In Srimad Bhagavatam, many minor points of history and geography are also mentioned which, although nonessential, support its conclusions. Whatever is unnecessary in Srimad-Bhagavatam is eliminated when its meaning reaches its purest and most intensified glory in the teachings of Sri Caitanya Mahaprabhu. So, if we are to consider the very gist of Srimad-Bhagavatam, we must study the life and precepts of Sri Caitanya Mahaprabhu. Just as the teachings of the great author of Srimad Bhagavatam, Srila Vyasadeva, were percolated by the realizations of Sukadeva Goswami, the essence of Srimad Bhagavatam has been percolated by the life and precepts of Sri Caitanya Mahaprabhu.
Sri Caitanya Mahaprabhu felt a great pain of separation from Krsna which burned like fire and was expressed as the Siksastakam.
Sri Caitanya Mahaprabhu has taught us that separation is the highest principle in divinity. Just as the most intense conception of ecstasy is association with Krsna, the most intense conception of pain is separation from Krsna. Yet the pain felt from Krsna's separation is far more intense than the ecstasy felt from His association. Sriman Mahaprabhu says, "Can't you understand the painful situation you are in? Your senses must have all been destroyed! Otherwise you would have died from the pain of separation from Krsna. It is inconceivable. We belong to Him wholesale. He is all in all to us/but we can't see Him. We are forcibly separated from Him. How can we tolerate this?" And Bhaktivinoda Thakura once said, "I can't tolerate separation from Krsna any longer. I can go on for only three or four more days, and then I shall have to leave this body."
To love Krsna means that we shall have to "die to live." In the beginning divine love seems like lava, death, but really it is nectar, life. Many persons in this ordinary world are also frustrated in love. They sometimes go mad and commit suicide because they can't tolerate the pain. But the pain which comes with separation from Krsna although compared with lava, is not injurious like lava. Kaviraja Goswami explains:
bahye visajvala haya bhitore anandamaya,
krsna premara adbhuta carite
"The wonderful characteristic of divine love of Krsna is that although externally, it works like fiery lava, internally it is like sweet nectar that fills the heart with the greatest joy."
Although He felt the greatest pain of separation from Krsna, still, within His heart, Sri Caitanya Mahaprabhu experienced the deepest ecstatic joy. The ecstatic symptoms manifested by Sri Caitanya Mahaprabhu have never been found in the history of the world or even expressed in any scripture. In Him, we find the highest conception of the Ultimate Reality. This is explained in my Prema Dhama Stotram (66):
atma-siddha-sava lila puma-saukhya-laksanam
prema-dhama-devam-eva naumi gaura-sundaram
"This is the all-conquering conclusion. The highest conception of the Ultimate Reality must also be the highest form of ananda, ecstasy. Sri Caitanya Mahaprabhu is Krsna, ecstasy Himself, tasting His own sweetness and dancing in ecstatic joy. His own holy name is the cause of His ecstasy, expressed as dancing, and the holy name is the effect of His ecstasy, expressed as chanting. The cause is the effect. The dynamo is creating ecstatic energy which makes Him dance, and His chanting distributes that ecstasy to others."
Swami B.R. Shridhara Maharaja