If I remember correctly, each alchemical ingredient has a component its made of like Arthas mentioned above. Aether is one of those types. There are several different ingredients that have the same component so it shouldn't be too hard to track down.
Oh! I get it! There is no ingredient called Aether, but instead several ingredients belong to the Aether family, so when a formula calls for Aether I just need something from the Aether category of ingredients.
Thanks for the clarification
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