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The strongest trees are rooted in the dark places of the earth. Darkness will be your cloak, your shield, your mother's milk. Darkness will make you strong.

George R. R. Martin (2012). “George R. R. Martin's A Game of Thrones 5-Book Boxed Set (Song of Ice and Fire Series): A Game of Thrones, A Clash of Kings, A Storm of Swords, A Feast for Crows, and and A Dance with Dragons”, p.3519, Bantam
The strongest trees are rooted in the dark places of the earth. Darkness will be your cloak, your shield, your mother's milk. Darkness will make you strong.