Believing things "on authority" only means believing them because you have been told them by someone you think trustworthy. Ninety-nine percent of the things you believe are believed on authority. I believe there is such a place as New York. I could not prove by abstract reasoning that there is such a place. I believe it because reliable people have told me so. The ordinary person believes in the solar system, atoms, and the circulation of the blood on authority because the scientists say so. Every historical statement is believed on authority. None of us has seen the Norman Conquest or the defeat of the Spanish Armada. But we believe them simply because people who did see them have left writings that tell us about them; in fact, on authority. A person who balked at authority in other things, as some people do in religion, would have to be content to know nothing all his life.