Ernest Renan trained for the priesthood, lost his faith over the historical criticism of scripture rather than over doctrine, and became the most controversial writer in France with the Life of Jesus in 1863. The book treats the Gospels as documents of their period, removes the miracles, and presents an incomparable man rather than a divine one. It sold enormously, cost him his chair at the Collège de France for seven years, and made him the emblem of everything the church was fighting.
His lecture of 1882, What is a Nation?, is the more durable work and the reason he belongs in political thought. The question was not academic: Germany had annexed Alsace-Lorraine in 1871 on the ground that its inhabitants were German by race and language, and Renan is answering that argument — Treitschke and Mommsen had made it explicitly. He goes through the candidates and rejects them all. Race is not it, since every European nation is a mixture and the philology of races has no relation to political nationality. Language is not it: Switzerland has three and is one nation, the Americas share theirs with Britain and are not. Religion is not it, nor geography, nor dynastic interest, nor material advantage, which would make a nation a customs union.
What remains is a spiritual principle with two parts, one in the past and one in the present: a rich legacy of memories held in common, and present consent, the will to continue to live together and to make the most of the inheritance received. A nation is a daily plebiscite, as the individual's existence is a perpetual affirmation of life.
He adds the observation the lecture is most quoted for now: forgetting, and even historical error, is essential to the creation of a nation, and the progress of historical study is often a danger to nationality, because every nation was founded on violence its members must agree not to remember.
The formulation gave civic nationalism its charter and remains the standard alternative to ethnic accounts, though Renan's own writings on Semitic peoples contain material that sits badly beside it.