Srimad-Bhagavatam: Canto 3 - Chapter 1 - Verse 5
करोति कर्माणि कृतावतारोयान्यात्मतन्त्रो भगवांस्त्र्यधीश: ।यथा ससर्जाग्र इदं निरीह:संस्थाप्य वृत्तिं जगतो विधत्ते ॥ ५ ॥
karoti karmāṇi kṛtāvatāroyāny ātma-tantro bhagavāṁs tryadhīśaḥyathā sasarjāgra idaṁ nirīhaḥsaṁsthāpya vṛttiṁ jagato vidhatte
O great sage, kindly narrate how the Supreme Personality of Godhead, who is the independent, desireless Lord of the three worlds and the controller of all energies, accepts incarnations and creates the cosmic manifestation with perfectly arranged regulative principles for its maintenance.
Lord Kṛṣṇa is the original Personality of Godhead from whom the three creative incarnations, namely the puruṣa-avatāras — Kāraṇārṇavaśāyī Viṣṇu, Garbhodakaśāyī Viṣṇu and Kṣīrodakaśāyī Viṣṇu — expand. The whole material creation is conducted by the three puruṣas in successive stages under the external energy of the Lord, and thus material nature is controlled by Him. Thinking material nature to be independent is like seeking milk from the nipplelike bags on the neck of a goat. The Lord is independent and desireless. He does not create the material world for His own satisfaction as we create our household affairs to fulfill our material desires. Actually the material world is created for the illusory enjoyment of the conditioned souls, who have been against the transcendental service of the Lord since time immemorial. But the material universes are full in themselves. There is no scarcity for maintenance in the material world. Because of their poor fund of knowledge, the materialists are disturbed when there is an apparent increase of population on the earth. Whenever there is a living being on the earth, however, his subsistence is immediately arranged by the Lord. The other species of living entities, who far outnumber human society, are never disturbed for maintenance; they are never seen dying of starvation. It is only human society that is disturbed about the food situation and, to cover up the real fact of administrative mismanagement, takes shelter in the plea that the population is excessively increasing. If there is any scarcity in the world, it is the scarcity of God consciousness; otherwise, by the grace of the Lord, there is no scarcity of anything.