In the Brihadaranyaka Upanishad what is the initial source of creation?

In the Brihadaranyaka Upanishad, the initial source of creation is described as the ultimate reality known as Brahman. It is depicted as a formless, undivided consciousness that undergoes a process of self-manifestation, leading to the creation of the universe. This source is often referred to as "the Self" or "Atman," emphasizing the interconnectedness of all existence and the idea that everything originates from this singular, divine essence.