The Taittirīya Upaniṣad

The source of the five sheaths — annamaya the food-made, prāṇamaya the breath-made, manomaya the mind-made, vijñānamaya the understanding-made, and ānandamaya the bliss-made — each described as being within the one before it, "of the same shape."

The wing's third model rests here, and this is a real ancient source, unlike the wheels. The pack keeps the contrast deliberate: the sheaths are Upaniṣadic, the six-wheel chart is late-medieval, and the modern presentation runs them together as if both came down from the same antiquity.