SB 1.10 - The Lord appears for the welfare of the world
The Personality of Godhead’s pastimes are described in the confidential parts of the Vedas by His great devotees. It is He only who creates, maintains and annihilates the material world and yet remains unaffected. The Lord is described throughout the Vedas but in the Bhāgavatam the confidential parts of His activities are described by the confidential devotee, Śukadeva Gosvāmī. In the Vedānta and Upaniṣads there is only a hint of the confidential parts of His pastimes. There the Lord is simply distinguished from the mundane conception of existence, and the less intelligent concludes He is impersonal. But factually He is the Supreme Person, Bhagavān.
When the rulers live like animals following adharma, the Lord manifests Himself and performs wonderful activities in transcendental forms as necessary in different periods and ages. He accepts forms for the welfare of the world in Vraja, Mathurā and Dvārakā in every day of Brahmā and displays His six powers, truth, pleasing words, mercy and good qualities. Everything in existence is the property of the Lord. The living beings are the parts and parcels of the Lord and have a right to live at the mercy of the Lord to execute their prescribed work. The king is the representative of the Lord to look after the management of the Lord’s will. Such kings have full responsibility and knowledge from authorities about the administration of the world.
But at times, due to influence of the mode of ignorance, the kings become irresponsible and live like animals for the sake of their own personal interest. This causes disturbances in society and the devotees of the Lord are also persecuted. At such times the Lord appears in His transcendental form to keep His creation in a normal condition. The material world is created to satisfy the whims of the conditioned souls. But when the souls exploit the resources of nature unlawfully, the Lord appears to chastise them and to protect the faithful. The Lord performs wonderful activities such as bridging the Indian ocean when He came as Rāma, killing powerful demons and marrying 16108 wives when He came as Kṛṣṇa and so on.