Advaita Acarya :Principle reason for Shri Chaitanya’s advent
As the life of Lord Chaitanya Mahaprabhu is very confidential and full of meaning so is the appearance and life of Shri Advaita Acharya whose appearance day is today(3rd February 2017). He is considered to be the principle reason for Shri Chaitanya’s advent. Whenever Krishna incarnates, so do his expansions, energies and confidential devotees. Since Lord Chaitanya is considered to be Krishna himself (in the mood of the greatest devotee, Shri Radha) we find that preceding him, as well as during and after his manifest “lila” or divine pastimes, his whole entourage of eternal associates came to facilitate his mission of spreading the “yuga-dharma” or the process of self-realization for this age--the congregational chanting of the holy names in joyous celebration.
Like Lord Chaitanya who is in the category of “Vishnu-tattva” or God, so is Shri Advaita, who has been identified in various Vaishnava writings as either Lord Maha-Vishnu (Who is the source and sustainer of infinite universes), or Sada-Shiva (the original form of Shiva, the great devotee and empowered destroyer), or both: Sada Shiva Maha Vishnu. So we can just simply equate him with God playing the part of a devotee of God, as does Lord Chaitanya and Nitai who are Krishna and Balarama, but playing the part of devotees and teaching us how to be Krishna conscious by their example.
Although God is one without a second, he expands himself unlimitedly to serve his different divine purposes. Though this fact can be confusing to those of us brought up with only one aspect or "face" of God, it does explain the infinite nature of the Sweet Absolute, and the varied understandings of him. The Shrimad Bhagavatam describes that in fact the incarnations of God are as uncountable as are the waves of the ocean. At the same time there is a Supreme original source of all these incarnations of Godhead.
This source is Shri Krishna: "All of the above-mentioned incarnations are either plenary portions or portions of the plenary portions of the Lord, but Lord Sri Krishna is the original Personality of Godhead. All of them appear on planets whenever there is a disturbance created by the atheists. The Lord incarnates to protect the theists." [SB 1.3.28] and Shri Krishna Chaitanya Mahaprabhu is none different from Lord Krishna.
Although the appearance of Lord Chaitanya was already destined in order to serve his internal purposes and as a “yuga-avatar”(incarnation who brings the process of God realization for the particular age), it appears from another angle of vision that he came at the behest of Shri Advaita Acharya. This demonstrates how much Krishna is affected by the pleading of and welfare for his pure devotees. We see in studying the different advents of God in the Vedas, that there are many simultaneous reasons for their appearance that have to be harmonized. In the Bhagavad-gita 4th chapter we read that God comes to Earth and presumably other planets to annihilate the miscreants and protect the devotees. Prabhupada and our Vaishnava acharyas have explained that Krishna has sufficient means through the material nature (natural calamities or diseases, etc.) to take care of those of demoniac tendencies, but he has to come personally to mitigate the separation his pure devotees feel for him.
Advaita Acharya could be considered the efficient cause of both Lord Chaitanya’s appearance and disappearance. Here is a Shrimad Bhagavatam [3.9.11]verse quoted in the Chaitanya Charitamrita in explaining the effect of Shri Advaita’s prayers: “O my Lord, You always dwell in the vision and hearing of Your pure devotees. You also live in their lotuslike hearts, which are purified by devotional service. O my Lord, who are glorified by exalted prayers, You show special favor to Your devotees by manifesting Yourself in the eternal forms in which they welcome You.” The Cc explains that verse as follows: “The essence of the meaning of this verse is that Lord Krsna appears in all His innumerable eternal forms because of the desires of His pure devotees.”