Read it through once

The Scot is always believed, yet he never tells anything but lies; whereas the captain is never believed, although he never tells a lie, so far as I can judge. If he should say his uncle was a male person, he would probably say it in such a way that nobody would believe it; at the same time the Scot could claim that he had a female uncle and not stir a doubt in anybody's mind. My own luck has been curious all my literary life; I never could tell a lie that anybody would doubt, nor a truth that anybody would believe.