Trisikhi Brahmana Upanishad belongs to the Shukla Yajur Veda. It is about a conversation between a brahmana named Trishakhi and Surya, the sun god, who explains to the former the distinction between the body and the soul and the means to achieve Kaivalya or liberation. He describes how Shiva, as the all-pervading Supreme Self, created the objective reality (Brahmam), which is a combination of Truth (sath), and ignorance and illusion, and how all the tattvas or principles, from mahat to the Mahabhutas, ensued from it.
He further explains how the elements manifest themselves as the twelve aspects of human personality. These twelve aspects of the beings are responsible for the bondage, attachment, births, and rebirths of individual souls but Sada Shiva only. But because of ignorance and pride, they cannot see the truth about themselves. It is only after taking birth hundreds of times, an individual aspires to become free from the world of illusion and ignorance.
With the constant yoga practice and by renouncing attachment to actions, he succeeds in sending the soul power into his head and becoming enlightened. The Upanishad also holds the view that Shiva is the only Truth and the rest is an illusion.