The Druids explained the physical as well as the spiritual sciences. They taught the secrets of the universe, the harmonious progress of the heavenly bodies, the formation of the earth, and above all – the immortality of the soul.
- Siphra Dzeniouta (The Book of Concealed Mystery) – Kabbalah
- The Popol Vuh (The Mythic and Heroic Sagas of the Kichés of Central America) – Kiche Manuscript
- Phaedrus – Plato
- Timaeus – Plato
- Aitareya Brahmanam – Vedas
