From Sounsyy's posts, I would recommend these, specifically the bolded ones. Do note that some of them contain links to other pages. It does mean going through the related links and their related links.
Crash Course in Eorzean Aetherology
- Aetherology 101 - What is Aether, the Lifestream, and the Aetherytes?
- Aetherology 102 - Corrupted Aether and Aethersickness
- Aetherology 201 - Schools of Magick, Aether Sources, Foci, and Channeling Aids
- Aetherology 202 - Essences & Permutations: A Treatise of the Six Elements
- Thaumaturgy 301 - Manipulating the Polarities Two, Astral versus Umbral
- Thaumaturgy 302 - The Religion of Thaumaturgy, The Order of Nald'thal
- Black Magic 701 - Origins of the Forbidden Black
- Conjury 402 - Hearers and the Elemental Religion of Nophica
Crash Course in Eorzean Aetherology
- Aetherology 101 - What is Aether, the Lifestream, and the Aetherytes?
- Aetherology 102 - Corrupted Aether and Aethersickness
- Aetherology 201 - Schools of Magick, Aether Sources, Foci, and Channeling Aids
- Aetherology 202 - Essences & Permutations: A Treatise of the Six Elements
- Thaumaturgy 301 - Manipulating the Polarities Two, Astral versus Umbral
- Thaumaturgy 302 - The Religion of Thaumaturgy, The Order of Nald'thal
- Black Magic 701 - Origins of the Forbidden Black
- Conjury 402 - Hearers and the Elemental Religion of Nophica