Taittirīyopaniṣat 02.10 and 11

Therefore, beyond this mind-made (manomaya), there is another inner essence composed of knowledge (vijñānamayaḥ). By that, this is complete. He is truly of the nature of a person. His personhood is continuity. He is established having, honest interest (śraddhā) is the head, ṛta (the order) is the right wing, satyam (truth, reality) is the left wing, yoga is the essence, and greatness is the tail.

Here is a verse about this: "Knowledge extends the sacrifice; it also extends actions. All the gods worship knowledge as the eldest Brahman. If one knows knowledge as Brahman and does not become heedless, having abandoned evil in the body, he attains all desires equally. This indeed is the bodily essence of him who was of the previous (one)."

Taittirīya Bhāshya 02.10 and 11

From the testimonial quoted, the following nuanced meanings come to light: 'śraddhā' - the honest interest, always upholds Vedas, i.e. knowledge; 'ṛtam' - is that order, which gives knowledge; 'satyam' - is the governing principle; 'yoga' - is the essence that allows all spheres to be experienced here, now; 'mahat' - the ego principle should become tail, i.e. left behind, when you come to 'vijñānamayaḥ' i.e. sphere of knowledge.

"... From that, Vāsudeva is within.

'śraddhā' - so named because it upholds the Veda, is regarded as the head in matters of host interest. The right hand, established in 'ṛtam', is considered the giver of knowledge.

Left hand, established in 'satya', from that, the truth, the good, and the reality is governed. Called 'yoga', as all the worlds are attained here, by yoga. The middle tail, called great (maho), as greatness is always in it."