Krishna is absolute truth without duality—His name, form, and presence are eternally one and non-different from Him.Listen — Srila Prabhupada Uvaca
Prabhupāda: So Lord Caitanya is describing about the personal feature of Lord Kṛṣṇa. The [im]personal feature of Lord Kṛṣṇa, as described in the Bhagavad-gītā, that is the manifestation of His material energy. Now, the personal feature as described by Lord Caitanya in the Caitanya-caritāmṛta, this is the description of His spiritual feature. We have already studied in the Bhagavad-gītā that the Lord has two distinctive features: material and spiritual, superior and inferior. Of course, for Him there is no superior or inferior.
But for us, it is superior, inferior. We cannot say that because everything is emanation from the Supreme, therefore there is no superior or inferior. No. Superior, inferior, in relationship with the energy. Just like īśvaraḥ sarva-bhūtānāṃ hṛd-deśe 'rjuna tiṣṭhati [Bg 18.61]: [The Supreme Lord is situated in everyone's heart, O Arjuna, and is directing the wanderings of all living entities, who are seated as on a machine, made of the material energy.] "Īśvara, the Supreme Lord, is situated in everyone's heart." So He is in the heart of a hog, of a dog, and the learned brāhmaṇa as well.
For Him there is no such discrimination what is hog, what is dog, what is brāhmaṇa, what is good, what is bad, because He is Absolute. But here we have to distinguish between the hog and the dog, at least so far the material body is concerned. So Lord Caitanya says, kṛṣṇera svarūpa-vicāra śuna, sanātana advaya-jñāna-tattva, vraje vrajendra-nandana [Cc Madhya 20.152] [O Sanātana, please hear about the eternal form of Lord Kṛṣṇa. He is the Absolute Truth, devoid of duality but present in Vṛndāvana as the son of Nanda Mahārāja.] He is addressing Sanātana Gosvāmī. You'll remember that this chapter, "Instruction to Sanātana Gosvāmī," was begun when Sanātana Gosvāmī, after his retirement, approached the Lord at Benares and surrendered himself and asked Him, "What I am?" So under that question, He is describing his relationship with Kṛṣṇa.
Kṛṣṇa. The jīvātmā, the living entity, is eternally servitor of Kṛṣṇa, and one should understand the nature of his master so that his service attitude, his affection, may be more intimate. Suppose I am serving at a place. I am engaged in a service to a master, but I do not know how big is my master. But when I understand the influence and opulence and greatness of my master, I become more devoted: "Oh, my master is so great." So therefore simply knowing, "God is great, and I have got some relationship with God," that is not sufficient.
You must know how much great He is. Of course, you cannot calculate, but as far as possible, you should know how great He is. So that greatness of Lord Kṛṣṇa is being described here by Lord Caitanya to His disciple, Sanātana Gosvāmī. Advaya-jñāna-tattva, vraje vrajendra-nandana. Advaya-jñāna-tattva.
Advaya-jñāna-tattva means He is Absolute. He is not relative. Here everything is relative, but "God" means He is Absolute. He has nothing to be dependent.
Here everything, we are all dependent. To understand something, to understand light, we have to understand darkness. To understand good, we have to understand what is bad. So here it is everything duality. So Kṛṣṇa is Absolute.