'There may be some, perhaps - I don't know that there are - who abuse his kindness,' said Mr. Wickfield. 'Never be one of those, Trotwood, in anything. He is the least suspicious of mankind; and whether that's a merit, or whether it's a blemish, it deserves consideration in all dealings with the Doctor, great or small.
But doubt is wily and cunning and never, as it is sometimes said to be, loud or defiant. It is unassuming and sly, not bold or assertive - and the more unassuming, the more dangerous.