In plain words
This is the great Ajñāna.
That is why divinity is there, at the level of our hearts. Such divinity, they said, is the Kṛṣṇa principle alone. Among all these names, Keśavāya namaḥ, Nārāyaṇāya namaḥ, Mādhavāya namaḥ, Madhusūdhanāya namaḥ, it has also concluded that the Name of Kṛṣṇa is the principle of the full Avatāra. It said Kṛṣṇa is the full embodiment, the full Avatāra. What is the reason for this? Though all the Avatāras are one, what is the special quality in calling this Kṛṣṇāvatāra alone the full Avatāra? There are no such distinctions among the Avatāras: this one a full Avatāra, this one a half Avatāra, an Avatāra of a time. In keeping with the time, according to place and person, taking account of the circumstances and conditions, the nature of the Avatāra shows only some things. Pūrṇamadaṃ, pūrṇamidaṃ pūrṇātpūrṇamudacyate: so all is fullness. We look only at the quantity and think, this is small, that is big. Here we must inquire into the quality, the fullness of it. In just the same way, in all the Avatāras too, divinity is nothing but fullness. But in some situations great scholars, going by the names and forms, have been giving it many kinds of meaning. Here there is a word, Kṛṣṇaḥ. Karṣaṇā iti Kṛṣṇa; but there are some other names in it too. In these five letters, ka, ra, ṣa, ṇa, a, infinite divinity is joined. We must recognise the inner meaning of ka. Ka means Kamalākānta. Besides this Kamalākānta, there is Kamaleśvara, Kamalagarbha; that is, the moment the sun rises, the lotuses open. Because of this there is Kamalabāndhava too. That is, the moment divinity arises in us, the lotus of the heart blossoms. So they took the letter ka as the principle of the sun, which makes things blossom. Ra, that is, what gives delight: they took it as the principle of Rāma. Ṣa they have held to be the principle of Viṣṇu, full of the six divine excellences. Ṇa they have held to be the Narasiṃha Avatāra. That is, they have held it to be the oneness of the two, man and beast. A means the One who is the akṣara itself, the One who has no decay. So, going only by such meanings of the letters, they have held that divinity is joined with this fullness, and that it is the Kṛṣṇāvatāra.
Some others have taken Kṛṣṇa as the principle of Ānanda. They called Him the embodiment of Sat, Cit and Ānanda. Kṛṣṇa means the dark one. Kṛṣṇa is none other than the embodiment of Sat, Cit and Ānanda who drives away Ajñāna.