“Whenever there is a decline of righteousness and rise of unrighteousness, then I manifest Myself! For the protection of the good, for the destruction of the wicked, and for the establishment of righteousness, I am born in every age.”
When unrighteousness grows and righteousness is on the wane, when the forces undivine seem to be stronger than the divine forces, when the Word of God or Commandments of His Messengers is forgotten or disobeyed, when religious fanaticism follows the letter of the scriptures killing their spirit, it is then that the Lord Incarnates Himself on earth, to save man, to save righteousness. He takes human form when He comes down on the physical plane. He is called an Avatara. An Avatara is a mighty person. He is like a great lake. He can remove the veil of ignorance of thousands of men and women, and can take them to the land of eternal rest, bliss and sunshine.The Avataras are one with the Supreme. They are not parts like the individual souls. Avataras or Incarnations are rays of the Lord.
When the work of Loka-Sangraha {the mission of elevating and helping humanity, or salvation of the world} is over, they disappear from the world.Some people want to have contact with Avataras without being endowed with proper qualifications. Even if an Avatara appears before you, you will not be able to find Him out. You have not got the eyes to see Him as such. You will take Him for an ordinary man only. How many were able to detect the divinity of Lord Krishna? …Very few people, like Bhishma, recognized Lord Krishna as the Avatara.
That is the reason why the Lord says: “The foolish disregard Me, when clad in human semblance, ignorant of My supreme nature, the great Lord of beings.”It is only a saint who can understand a saint. Only a Jesus can understand a Jesus. How can a patient know the merits of a doctor?