In Vortex, Abeloth's stated desire was to undo what Jacen did.
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Killing the Jedi princess and driving Luke dark would do that, especially if the former caused the latter.
"Trust not the words of a poet, as he is born to seduce. Yet for poetry to seize the heart, it must ring with the chimes of truth.”
“The world is understood through metaphors. Language is a metaphor-system. Mathematics is a metaphor-system. All real-world schools of magic and religion revolve around the understanding of vast metaphor-systems, symbols as they relate to concepts."
"See, the thing is, everything everyone tells you is a lie. The truth is always bigger than the words we use to describe it."