Notes transcribed from a lecture given December 21, 1966.
Lord Chaitanya is describing the Leela Avatars. There are innumerable avatars: Rama Nrsimha, Kalki, etc. In Srimad Bhagavatam some names are mentioned. All the incarnations, and especially the Leela avatars, descend to settle disturbances caused by demons.
There are, for these purposes, two types of men: devotees and demons. The devas (devotees) are demigods; they are completely Krishna conscious, and are entrusted with universal management. The demons or asuras (atheists) are meant for creating disturbances. When the number of asuras greatly increases and life becomes intolerable for the devas, then the Lord comes in the form of one of His plenary expansions. As stated in the Bhagavad Gita, "Just to deliver the faithful and to annihilate the unfaithful, I come in every millenium." This is the function and purpose of the Leela avatars.
Lord Chaitanya tells Sanatan Goswami that He will now speak of incarnations of material qualities, the Guna Avatars. Each quality of material nature is controlled by the Supreme Lord in His expansions as Vishnu, Who is a full plenary expansion of God with 94% of the known godly qualities; Lord Shiva, a pure devotee, has 84% of the godly qualities, and Brahma, who is a living entity (like ourselves) with 78% of the godly qualities. Each one is a part and parcel of the Lord (Krishna). The guna avatars are in charge of material affairs. Lord Shiva is the avatar of Ignorance but he is not ignorant, just as a prison official visiting the prison is not subject to its rules. Similarly, Brahma creates and initiates passion comes from Brahma. Vishnu maintains these and all plural eternals in the material sphere but He is the singular eternal.
What is the constitution of Brahma? There are innumerable living entities. Many of them are devotees, but they want to enjoy the material world and take favor from God. Brahma is in this position. Sometimes Krishna Himself becomes Brahma, when suitable living entities are not available. Just as a diamond has the power to illuminate, its power to shine being derived from the sun, so the powerful creator Brahma inherits power from the Supreme Lord. Brahma's power is tiny in comparison; it is not originally luminous like the sun. This material universe is created by him at certain intervals, stays for some time, and then is destroyed.
As with Brahma, sometimes when Lord Shiva is not available, Krishna accepts management of the modes of ignorance. Shiva is a direct expansion of God, but because He is in the department of ignorance he is not quite God. Shiva means auspicious. His business is destruction. There is a popular statue of Shiva dancing, surrounded by the fires of annihilation. Material energy is under the control of Shiva. Shiva is the father and material energy (Durga) is the mother. Because, unlike Krishna, Shiva has this connection with illusory energy, Shiva is not quite God. He stands between the living entity and Krishna. Lord Chaitanya quotes the Brahma Samhita on Lord Shiva: "If you mix something sour with milk, it becomes yogurt; such is the difference between Krishna and Shiva." Once made into yogurt it cannot be changed back into milk, although it has the same constitution. Those who worship Shiva cannot derive the same benefits as those in Krishna consciousness. Shiva is not different from Krishna, but he is altered by his association with matter as he takes on the jobs of destruction and tamas (ignorance) management.
Vishnu is never in touch with material energy. Vishnu is beyond the material worlds. Sankaracharya accepted this Supreme position of Narayana (Vishnu), although he was an impersonalist. Therefore, Vishnu's Body is Sat–Chit–Ananda, full of knowledge, eternal, and blissful.