If there is really such a state in the world: the soul is very full and peaceful, neither nostalgic for the past nor the future, allowing time to pass and only grasping the present, without a sense of hope or enjoyment, unhappy or sorrowful, neither seeking nor fearing, but only feeling one's own existence, a person in this state can say that he has achieved happiness. —— Rousseau, "The Dream of a Lonely Walker"