CC Madhya 20.153
cid-ānanda-deha, sarvāśraya, sarveśvara
“Kṛṣṇa is the original source of everything and the sum total of everything. He appears as the supreme youth, and His whole body is composed of spiritual bliss. He is the shelter of everything and master of everyone.
Kṛṣṇa is the origin of all viṣṇu-tattvas, including Mahā-Viṣṇu, Garbhodakaśāyī Viṣṇu and Kṣīrodakaśāyī Viṣṇu. He is the ultimate goal of Vaiṣṇava philosophy. Everything emanates from Him. His body is completely spiritual and is the source of all spiritual being. Although He is the source of everything, He Himself has no source. Advaitam acyutam anādim ananta-rūpam/ ādyaṁ purāṇa-puruṣaṁ nava-yauvanaṁ ca. Although He is the supreme source of everyone, He is still always a fresh youth.