Odin (from Hávamal)
“The mind alone knows what lies near the heart,
he is alone with his spirit;
no sickness is worse for the sensible man
than to find no contentment in anything.”
- This quote comes from stanza 95 of Hávamál (Sayings of the High One), an old poem which was preserved in the 13th-century Poetic Edda, produced anonymously in Iceland. The translation is by Carolyne Larrington (Oxford University Press, 2014).