Answering question first, the way I see it is that every witch has the ability to learn any type of magic but depending on their soul it shows what they are more gauged to. Like an old would can learn dark or natural but it would be exceedingly difficult where as a balanced soul, since they are gauges to both old and dark would just have difficulty learning natural magic above all else. I see Restless souls having specific gauges too like Lia has a gauge for both old and dark magic but had difficulty learning natural too which is why she believed herself to be a balanced soul for so long. It depends on the witch and how they are gauged. Its just something that started making sense to me because if you think about it, everything requires all forms of magic. I hope you don't mind.

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Aless will nod. "Oh most definitely."

Then she'll look at Kat, "You have a good teacher though. I'm sure she could teach you everything she knows if you'd be willing to deal with how she teahes each thing, which obviously you are." 

Lia will step on and Atticus will just look over Mitch and Roland. "Nice. I'm still the prettiest." He'll joke. 

Lia will just smirk at Mitch and Aless will walk over and pull the braid out of Lia's hair. "Nothing unnatural please." She'll say and Aless will nod and as she runs her fingers through Lia's hair it will turn red. Lia will look at the ends of it and shrug. "Not bad."