Weltschmerz was a term in psychology used to describe a kind of pessimistic world view held by one who believes their reality can never adequately satisfy the demands of the mind. Doctor Elizabeth Dehner felt Yoshi Nakamura was experiencing Weltschmerz while contemplating what Sorahl had told him about Vulcan, and realizing that theirs was a society he wished to belong to. (TOS novel: Strangers from the Sky)