"In the remote days before the Foundation you could not build your own spaceship without a Captain to sail her in space. One had the idea of hire other people to build them. At those times it was very rare to see a sailor owing more than a few hundred ships. But then there had been at Trantor a little revolution in the rooms of the Captains Union, so that now a ship may be acquired even without a Captain but she cannot actually sail".

(Isaac Asimov - The Secrets of Avonmora and Other Stories)