Duty is a debt you owe to yourself to fulfill obligations you have assumed voluntarily.
Specialization is for insects.
Its very variety, subtlety, and utterly irrational, idiomatic complexity makes it possible to say things in English which simply cannot be said in any other language.
Don't explain computers to laymen. Simpler to explain sex to a virgin.
He never gave up his search for the Door into Summer.
All cats are not gray after midnight.