Srimad Bhagavatam Canto 11, Chapter 05, Text 35

SB 11.5.35

evam yuganurupabhyam
 bhagavan yuga-vartibhih
manujair ijyate rajan
 sreyasam isvaro harih
 
Translation by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada: 
 
Thus, O King, the Supreme Lord Hari is the giver of all desirable benefits of life. Intelligent human beings worship the particular forms and names that the Lord manifests in different ages.
 
Purport by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada: 
 
The word yuganurupabhyam is significant here. Anurupa means “suitable” or “appropriate.” The Supreme Personality of Godhead, Krsna, anxiously desires that all conditioned living entities come back home, back to Godhead, for an eternal life of bliss and knowledge. Thus, the Lord reveals Himself in each of the four ages — Satya, Treta, Dvapara and Kali — in a form appropriate for worship by the human beings of that age. In his Laghu-bhagavatamrta (Purva-khanda 1.25), Srila Rupa Gosvami states:
 
kathyate varna-namabhyam
 suklah satya-yuge harih
raktah syamah kramat krsnas
 tretayam dvapare kalau
 
“The Supreme Lord Hari is described in terms of His color and names as sukla [white, or the most pure] in Satya-yuga, and as red, dark blue and black respectively in Treta, Dvapara and Kali.” Thus, although in each age various names suitable for glorifying the Lord are given, such as Hamsa and Suparna in Satya-yuga, Visnu and Yajña in Treta-yuga, and Vasudeva and Sankarsana in Dvapara-yuga, similar names are not given for Kali-yuga, although such names exist, in order to avoid disclosing cheaply the truth of the incarnation of Sri Caitanya Mahaprabhu.
 
In Kali-yuga human society is infested with hypocrisy and superficiality. There is a strong tendency toward imitation and fraud in this age. Therefore the incarnation of Sri Caitanya Mahaprabhu is revealed in Vedic literature in a confidential, discrete way, so that it will be known to the authorized persons who can then propagate the mission of the Lord on the earth. We actually see in this modern age that many foolish and ordinary persons claim to be God or incarnations, avataras, etc. There are many cheap philosophies and academies that promise, for a moderate fee, to make one God in a short time. In America one famous religious group promises its followers that they will all become the Supreme Lord in heaven. Such bogus preaching goes on in the name of Christianity. Thus, were Caitanya Mahaprabhu’s name widely spoken of in Vedic literature, there would soon be a veritable plague of imitation Caitanya Mahaprabhus infesting the world.
 
Therefore, to prevent this pandemonium, discretion is exercised in the Vedic literatures in Kali-yuga, and in a sober, concealed way the actual followers of Vedic culture are informed through the Vedic mantras of the descent of Sri Caitanya Mahaprabhu. This discrete system, selected by the Lord Himself for His appearance in Kali-yuga, is proving to be greatly successful on the earth planet. And throughout the world millions of people are chanting the holy names of Krsna without the unbearable harassment of hundreds and thousands of imitation Caitanya Mahaprabhus. Those who seriously desire to approach the Supreme Personality of Godhead can easily understand the Lord’s mission, whereas cynical materialistic rascals, puffed up by false prestige and madly considering their insignificant intelligence to be greater than the intelligence of Lord Krsna, cannot understand the beautiful arrangements made by the Lord for His graceful descent into the material world. Thus, although Krsna is sreyasam isvarah, or the Lord of all benedictions, such foolish persons turn away from the Lord’s mission and in this way deprive themselves of their own true benefit in life.
Srimad Bhagavatam Canto 11, Chapter 05, Text 34
Srimad Bhagavatam Canto 11, Chapter 05, Text 36