The inner reasons for Śrīman Mahāprabhu’s appearance and shastric reference
According to Śrīman Mahāprabhu’s intimate associate Śrīla Svarūpa Dāmodara, there were three unfulfilled desires, which were the main causes for Śrī Kṛṣṇa to accept the mood and complexion of Śrīmatī Rādhārānī and to descend as Śrī Caitanya Mahāprabhu. It is thus described in Śrī Svarūpa Gosvāmī’s notebook:
śrī rādhāyāḥ praṇaya mahimā kīdṛśo vānayair vā
svādyo yenādbhuta madhurimā kīdṛśo vā madīyaḥ
saukhyaṁ cāsyā mad anubhavataḥ kīdṛśaṁ veti lobhās
tad bhāvāḍhyaḥ samajani śacī garbha sindhau harīnduḥ
“How glorious is Śrī Rādhā love for Me? How does She relish My wonderful sweetness through this love? How much bliss does She experience from relishing My sweetness?”
With these three kinds of sacred greed, Lord Hari, enriched with the feelings of Śrīmatī Rādhikā, appeared like the moon from mother Śacī’s ocean-like womb! To relish this threefold happiness, Vrajendra-Nandana appeared in the holy abode of Navadvīpa in Gauḍa-deśa (West-Bengal) as Śrī Gaurasundara in the first phase of Kali-yuga, with the mood and the golden complexion of Śrīmatī Rādhikā, and He was filled with unprecedented devotional mellows. In scriptures like the Śrutis, Smṛtis, Purāṇas, Saṁhitās as well as Śrīmad Bhāgavata, we can find lots of evidence about Śrī Gaurāṅga being the Original Personality of Godhead.
In the 6th Prapāṭhaka of the Puruṣa Bodhinī Śrūti in the Atharva Veda it is seen:
saptame gaura varṇa viṣṇor
ityanena sva śaktyā caikyam
etya prānte prātar avatīrya
saha dvaiḥ svam anuśikṣayati
“In the 7th Manvantara, or the Vaivasvata Manvantara, Śrī Kṛṣṇa will attain oneness with the essence of His pleasure potency, Śrī Rādhā, and will descend with His associates in the first part of the Kali – age to teach His devotees the hare-kṛṣṇa-kīrtana.” In the Śvetāśvatara Upaniṣad (3.12) we see:
mahān prabhur vai puruṣaḥ sattvasyaiṣa pravartakaḥ
sunirmalam imāṁ prāptim īśāno jyotir avyayaḥ
“He who promulgates sattva or viśuddha sattva is Mahāprabhu. He is the greatest puruṣa, or human-shaped avatāra. This Īśāna, Who is most pure, meaning free from desires for personal happiness like sense gratification or liberation, and who just bestows pure prema bhakti, is effulgent and eternal.” In the Muṇḍakopaniṣad (3.1.3) we find these words:
yadā paśyaḥ paśyate rukma varṇaṁ
kartāram īśaṁ puruṣaṁ brahma yonim
tadā vidvān puṇya pāpe vidhūya
niranjanaḥ paramaṁ sāmyam upaiti
Bhāvārthaḥ: Simply by being initiated in the mantra of this mahā puruṣa, Who has a golden complexion, Who is the only performer of creation, maintenance and destruction and the bestower of all benedictions, Who descended in a human form in a brāhmaṇa-family, a human being can become free from material life, which consists of piety and virtue. The threefold miseries, such as ādhyātmika, are then uprooted and he will be blessed with the supreme peace.”
A meditation on Śrī Gaurāṅga is described in the Uttara Vibhāga (63) of the Gopāla Tāpanī Śruti:
hiranmayaṁ saumya-tanuṁ sva bhaktāyābhaya-pradam
dhyayen manasi māṁ nityaṁ veṇu śṛṅgadharaṁ tu vā
“Always meditate on Mahāprabhu, the sannyāsī Who carries a bamboo rod, Whose brāhmaṇa-body is of golden complexion and Who bestows fearlessness upon His devotees.” The Bṛhan Nāradīya Purāṇa says (5.35):
aham eva kalau vipra nityaṁ prachanna vigrahaḥ
bhagavad bhakta rūpeṇa lokān rakṣāmi sarvadā
The Lord said: “O brāhmaṇa! I always protect all people in the age of Kali in a hidden form as a devotee – meaning, I cover My body with the complexion and the bhāva of Śrī Rādhā.” Śrī Kṛṣṇa says in an Upapurāṇa:
aham eva kvacid brahman sannyāsāśramam āśritaḥ
hari bhaktiṁ grāhayāmi kalau pāpa hatan narān
“O brāhmaṇa! In the Kali-yuga (the one appearing in the 28th Catur-yuga at the end of the Vaivasvata Manvantara), I always take shelter of the sannyāsa-āśrama to bestow Hari-bhakti to the sinful people.”
In the ninth Paṭala of the Kapila Tantra, it is seen how Śrī Kṛṣṇa shows to Śrī Rādhā His Gaura-vigraha in a dream, which is full of bhakti rasa and which is endowed with Her bhāva and luster,:
rādhā bhāva kānti yutāṁ mūrtim ekāṁ prakāśayan
svapne tu darśayāmāsa rādhikāyai svayaṁ prabhuḥ
In the Śrī Viṣṇu-sahasra-nāma-Stotram, the omniscient Mahā-Muni Śrī Vaiśampāyana has clearly mentioned Śrī Gaurāṅga’s avatāra
suvarṇa varṇo hemāṅgo varāṅga candanāṅgadī
sannyāsa kṛc chamaḥ śāntaḥ niṣṭhā śānti parāyaṇaḥ
In Śrī Caitanya Caritāmṛta (Ādī 3) we can find a very beautiful explanation of this verse:
tāpta hema sama kānti – prakāṇḍa śarīra;
ājānulambita bhuja – kamala locana;
tila phula jini nāsā – sudhāṁśu vadana
śānta dānta kṛṣṇa bhakti niṣṭhā parāyaṇa;
bhakta vatsala, suśīla sarva bhūte sama
candanera aṅgada bālā, candana bhūṣaṇa;
nṛtya kāle pori korena kṛṣṇa saṅkīrtana
“His powerful body has the luster of molten gold, His arms stretch down to His knees and He has lotus like eyes. His nose is more beautiful than a sesame flower and His face shines like the moon. He is peaceful, self-controlled, and fixed in devotion to Kṛṣṇa. He is kind upon the devotees, well-mannered and equipoised to all living beings. His ornaments, which He wears during the performance of Kṛṣṇa-saṅkīrtana, are made of sandalwood.”
In the Ūrdhāmnāya Saṁhitā is written:
kalau purandarāt śacyāḥ gaura rūpo vibhuḥ smṛtaḥ
mahāprabhur iti khyātaḥ sarva lokaika pāvanaḥ
“In the age of Kali, the Lord will descend in a golden form from Jagannātha Miśra and Śacī-devī and will become famous as ‘Mahāprabhu’, the purifier of the whole world”.
In Śrīmad Bhāgavata, the essence of the Vedānta, Śrī Prahlāda Mahāśaya has mentioned, that Śrī Gaurāṅga will come, concealing His original form with the bhāva and luster of His Beloved –
itthaṁ nṛ-tiryag ṛṣi deva ṛṣāvatārair
lokān vibhāvayasi haṁsi jagat pratīpān
dharmaṁ mahāpuruṣa pāsi yugānuvṛttaṁ
channaḥ kalau yad abhavas tri-yugo’tha sa tvam
Śrī Prahlāda Mahāśaya said: “O Mahā-puruṣa! In this way, You descend as a human being, as an animal, a sage, a demigod and a fish to protect the people and to destroy the demons, who wish to wreak havoc. Thus You protect religious principles according to the yuga. But in the Kali-yuga You are channa, hidden, and (although You are not openly manifest to protect the saints and destroy the demons like in other Yugas) You promulgate the Yuga-dharma of Śrī Harināma-Saṅkīrtana. Hence You are known as Tri-yuga: He who openly descends in the Satya-, Tretā- and Dvāpara-yuga and who descends in a hidden way in the Kali-yuga.” (Bhāg. 7.9.38)
When Śrī Garga Muni, who is a trikāla-darśī (seer of past, present and future), performed the name-giving ceremony of Śrī Kṛṣṇa, he clearly predicted a golden complexioned avatāra in the age of Kali –
āsan varṇās trayo hyasya gṛhṇato’nuyugaṁ tanuḥ
śuklo raktas tathā pīta idānīṁ kṛṣṇatāṁ gataḥ
Śrī Gargācārya said: “O Nanda! This son of Yours descends age after age and in each age He has another complexion. In the Satya-yuga He is white, in Tretā He is red and in Kali yuga He is yellow. Now, in Dvāpara-yuga He has attained a blackish complexion.”
These words of Garga indicate, that Bhagavān will appear in Kali-yuga as Śrī Gaurāṅga. One of the omniscient Nava Yogendras, Ṛṣi Kara-bhājana, clearly mentioned Śrī Gaurāṅga and His associates when he told Mahārāja Nimi about the avatāras in Kali:
kṛṣṇa-varṇaṁ tviṣākṛṣṇaṁ sāṅgopāṅgāstra pārṣadam
yajñaiḥ saṅkīrtana prāyair yajanti hi sumedhasaḥ
Śrīmat Kavirāja Gosvāmīpāda revealed a very beautiful explanation of this verse:
śuno bhāi! ei sab caitanya-mahimā;
ei śloka kohe tāra mahimāra sīmā
‘kṛṣṇa’ ei dui varṇa sadā yāra mukhe;
athavā kṛṣṇake teṅho varṇe nija sukhe
kṛṣṇa-varṇa śabdera artha dui to pramāṇa;
kṛṣṇa vinu tāra mukhe nāhi āise āna
keho tāre bole yadi ‘kṛṣṇa-varaṇa’;
āra viśeṣaṇe tāra kore nivāraṇa
deha kāntye hoy teṅho akṛṣṇa-varaṇa;
akṛṣṇa varaṇe kohe – pīta varaṇa
“O brother, listen to all the glories of Śrī Caitanya! This verse describes the limit of His glories! The two syllables kṛ-ṣṇa are always in His mouth, or: He always describes Kṛṣṇa for His own bliss. There are two meanings of the word kṛṣṇa-varṇa. Nothing else but Kṛṣṇa comes from His mouth. If someone tries to describe Him as being of blackish complexion, the other adjective (tviṣa akṛṣṇaṁ) will stop him. His complexion is not blackish. Actually the word akṛṣṇa varṇa means that He is yellow.”
jīvera kalmaṣa tamo nāśa koribāre;
aṅga upāṅga nāma nānā astra dhare
bhaktira virodhī – karma dharma vā adharma;
tāhāra kalmaṣa nāma – sei mahātama
bāhu tuli hari boli prema dṛṣte cāya;
koriyā kalmaṣa nāśa premete bhāsāya
śrī aṅga śrī mukha yei kore daraśana;
tāra pāpa kṣaya hoy pāy prema dhana
anya avatāre saba sainya śastra saṅge;
caitanya kṛṣṇera sainya aṅga upāṅge
aṅgopāṅga astra kore sva kārya sādhana;
aṅga śabdera artha āra śuno diyā mana
“He wears different weapons, named aṅga and upāṅga (His associates and devotees), to destroy the darkness of the peoples’ kalmaṣa. These kalmaṣas are the irreligious or religious activities, which are opposed to the principles of pure devotion – this is compared to deep darkness.
Raising His arms and saying ‘Hari’, He looks around with great love, destroying kalmaṣas and making everyone float in prema. The sins of anyone, who simply sees His divine body and His divine face, are destroyed and they attain the treasure of prema. All other avatāras appear with armies and weapons, but the army of Śrī Kṛṣṇa Caitanya consists of His devotees and associates. With these weapons He accomplishes His work. Now listen to another meaning of the word aṅga:”
advaita nityānanda caitanyera dui aṅga;
aṅgera avayava gaṇa kohiye ‘upāṅga’
aṅgopāṅga tīkṣṇa astra prabhura sahite;
sei sab astra hoy pāṣaṇḍa dalite
nityānanda gosāi – sākṣāt haladhara;
advaita ācārya gosāi sākṣāt īśvara
śrīvāsādi pāriṣada sainya saṅge loiyā;
dui senāpati bule kīrtana koriyā
pāṣaṇḍa dalana-bānā nityānanda rāya;
ācārya huṅkāre pāpa pāṣaṇḍī palāya
saṅkīrtana pravartaka śrī kṛṣṇa caitanya;
saṅkīrtana yajñe tāre sei dhanya
sei to sumedhā āra kubuddhi saṁsāra;
sarva yajña hoite kṛṣṇa nāma yajña sāra
“Advaita and Nityānanda are Lord Caitanya’s two aṅgas (limbs), and the different other limbs are called upāṅga. With these sharp weapons of His aṅgas and upāṅgas the Lord pierces the atheists and heretics. Nityānanda Gosāi is Balarāma Himself and Advaita Gosāī is Lord Śiva Himself. Taking along these two generals and His troops, consisting of associates like Śrīvāsa, He wanders around performing saṅkīrtana. Nityānanda Rāya is the destroyer of the atheists and heretics and the roaring of (Advaita) Ācārya Gosāī causes the sins of the atheists to flee.
Śrī Kṛṣṇa Caitanya promulgates the saṅkīrtana, and those who are blessed take part in that saṅkīrtana sacrifice. These people are intelligent, while the fools remain in material existence. Of all sacrifices the Kṛṣṇa-nāma yajña is the best.”
(C.C. Ādi Chapter 3)
taken from here