It is said, traiguṇya-viṣayā vedā nistraiguṇyo bhavārjuna. Unless one is situated in transcendence, one cannot understand the transcendental nature of the Lord. As stated in Śrīmad-Bhāgavatam (10.14.29):

athāpi te deva padāmbuja-dvaya-
 prasāda-leśānugṛhīta eva hi
jānāti tattvaṁ bhagavan-mahimno
 na cānya eko ’pi ciraṁ vicinvan

Only by the mercy of the Supreme Personality of Godhead can one understand Him. Those who are in the modes of material nature, although speculating for thousands of years, cannot understand Him. The Lord has innumerable forms (rāmādi-mūrtiṣu kalā-niyamena tiṣṭhan), and unless these forms, such as Lord Rāmacandra, Nṛsiṁhadeva, Kṛṣṇa and Balarāma, were transcendental, how could they be worshiped by devotees since time immemorial? Bhaktyā mām abhijānāti yāvān yaś cāsmi tattvataḥ (Bg. 18.55). Devotees who awaken their transcendental nature in the presence of the Lord and who follow the rules and regulations of devotional service can understand Lord Kṛṣṇa, Lord Rāmacandra and other incarnations, who are not of this material world but who come from the spiritual world for the benefit of people in general. If one does not take to this process, one imagines or manufactures some form of God according to material qualities and can never awaken a real understanding of the Supreme Personality of Godhead. The words bhaktyā mām abhijānāti yāvān yaś cāsmi tattvataḥ signify that unless one worships the Lord according to the regulative devotional principles, one cannot awaken the transcendental nature. Deity worship, even in the absence of the Supreme Personality of Godhead, awakens the transcendental nature of the devotee, who thus becomes increasingly attached to the Lord’s lotus feet.

The appearance of Kṛṣṇa is the answer to all imaginative iconography of the Supreme Personality of Godhead. Everyone imagines the form of the Supreme Personality of Godhead according to his mode of material nature. In the Brahma-saṁhitā it is said that the Lord is the oldest person. Therefore a section of religionists imagine that God must be very old, and therefore they depict a form of the Lord like a very old man. But in the same Brahma-saṁhitā, that is contradicted; although He is the oldest of all living entities, He has His eternal form as a fresh youth. The exact words used in this connection in the Śrīmad-Bhāgavatam are vijñānam ajñāna-bhidāpamārjanam. Vijñāna means transcendental knowledge of the Supreme Personality; vijñāna is also experienced knowledge. Transcendental knowledge has to be accepted by the descending process of disciplic succession as Brahmā presents the knowledge of Kṛṣṇa in the Brahma-saṁhitā. Brahma-saṁhitā is vijñāna as realized by Brahmā’s transcendental experience, and in that way he presented the form and the pastimes of Kṛṣṇa in the transcendental abode. Ajñāna-bhidā means “that which can match all kinds of speculation.” In ignorance, people are imagining the form of the Lord; sometimes He has no form and sometimes He has form, according to their different imaginations. But the presentation of Kṛṣṇa in the Brahma-saṁhitā is vijñāna — scientific, experienced knowledge given by Lord Brahmā and accepted by Lord Caitanya. There is no doubt about it. Śrī Kṛṣṇa’s form, Śrī Kṛṣṇa’s flute, Kṛṣṇa’s color — everything is reality. Here it is said that this vijñānam is always defeating all kinds of speculative knowledge. “Therefore,” the demigods prayed, “without Your appearing as Kṛṣṇa, as You are, neither ajñāna-bhidā (the nescience of speculative knowledge) nor vijñānam would be realized. Ajñāna-bhidāpamārjanam — by Your appearance the speculative knowledge of ignorance will be vanquished, and the real, experienced knowledge of authorities like Lord Brahmā will be established. Men influenced by the three modes of material nature imagine their own God according to the modes of material nature. In this way God is presented in various ways, but Your appearance will establish what the real form of God is.”

The highest blunder committed by the impersonalist is to think that when the incarnation of God comes, He accepts a form of matter in the mode of goodness. Actually the form of Kṛṣṇa or Nārāyaṇa is transcendental to any material idea. Even the greatest impersonalist, Śaṅkarācārya, has admitted, nārāyaṇaḥ paro ’vyaktāt: the material creation is caused by the avyakta, the impersonal manifestation of matter or the nonphenomenal total reservoir of matter, and Kṛṣṇa is transcendental to that material conception. This is expressed in the Śrīmad-Bhāgavatam as śuddha-sattva, or transcendental. The Lord does not belong to the material mode of goodness, for He is above the position of material goodness. He belongs to the transcendental, eternal status of bliss and knowledge.

“Dear Lord,” the demigods prayed, “when You appear in Your different incarnations, You take different names and forms according to different situations. Lord Kṛṣṇa is Your name because You are all-attractive; You are called Śyāmasundara because of Your transcendental beauty. Śyāma means blackish, yet they say that You are more beautiful than thousands of cupids. Kandarpa-koṭi-kamanīya. Although You appear in a color which is compared to that of a blackish cloud, You are the transcendental Absolute, and therefore Your beauty is many, many times more attractive than the delicate body of Cupid. Sometimes You are called Giridhārī because You lifted the hill known as Govardhana. You are sometimes called Nanda-nandana or Vāsudeva or Devakī-nandana because You appear as the son of Mahārāja Nanda or Devakī or Vasudeva. Impersonalists think that Your many names or forms are according to a particular type of work and quality because they accept You from the position of a material observer.

“Our dear Lord, the way of understanding is not to study Your absolute nature, form and activities by mental speculation. One must engage himself in devotional service; then one can understand Your absolute nature and Your transcendental form, name and quality. Actually, only a person who has a little taste for the service of Your lotus feet can understand Your transcendental nature or form and quality. Others may go on speculating for millions of years, but it is not possible for them to understand even a single part of Your actual position.” In other words, the Supreme Personality of Godhead, Kṛṣṇa, cannot be understood by the nondevotees because there is a curtain of yoga-māyā which covers Kṛṣṇa’s actual features. As confirmed in the Bhagavad-gītā (7.25), nāhaṁ prakāśaḥ sarvasya. The Lord says, “I am not exposed to anyone and everyone.” When Kṛṣṇa came, He was actually present on the Battlefield of Kurukṣetra, and everyone saw Him. But not everyone could understand that He was the Supreme Personality of Godhead. Still, everyone who died in His presence attained complete liberation from material bondage and was transferred to the spiritual world.

Because foolish mūḍhas do not awaken their spiritual nature, they do not understand Kṛṣṇa or Rāma (avajānanti māṁ mūḍhā mānuṣīṁ tanum āśritam). Even big academic scholars, not considering the endeavors of the ācāryas who have recommended devotional service in many elaborate commentaries and notes, think that Kṛṣṇa is fictitious. This is due to a lack of transcendental knowledge and a failure to awaken Kṛṣṇa consciousness. One should have the common sense to ask why, if Kṛṣṇa or Rāma were fictitious, stalwart scholars like Śrīdhara Svāmī, Rūpa Gosvāmī, Sanātana Gosvāmī, Vīrarāghava, Vijayadhvaja, Vallabhācārya and many other recognized ācāryas would have spent so much time to write about Kṛṣṇa in notes and commentaries on Śrīmad-Bhāgavatam.