Srimad Bhagavatam #15: The Lord is the cause of all causes

Being present inside each universe as Gabodakasayi Vishnu and Ksirodakasayi Vishnu, the Lord is the foundation upon which the whole material creation rests. Everything is created and maintained by His energy. The Lord is thus called the virat-purusha, the enjoyer of the cosmic manifestation, since everything is generated from His energy, and ultimately everything exists to satisfy Him. Because the universal form, or virat-rupa is described as a form of the Lord, the terms virat-rupa and virat-purusha are used more or less interchangeably.
In the first chapter, it was mentioned that Lord Brahma meditated in the universal form, the virat-rupa, to remember how to create the universe. As we also studied, there are two processes of creation: the primary creation, performed by Lord Maha-Vishnu, and the secondary creation, performed by Lord Brahma. The universal form exists even before the creation of the universe as part of the primary creation, a concept or model that guides the creation of Brahma. By meditating in this form, Brahma obtained all the necessary knowledge to recreate the universe the way it was before.