A very little key will open a very heavy door.

Marley was dead, to begin with. There is no doubt whatever about that. The register of his burial was signed by the clergyman, the clerk, the undertaker, and the chief mourner. Scrooge signed it. And Scrooge's name was good upon 'Change for anything he chose to put his hand to. Old Marley was as dead as a door-nail.

An observer of men who finds himself steadily repelled by some apparently trifling thing in a stranger is right to give it great weight. It may be the clue to the whole mystery. A hair or two will show where a lion is hidden. A very little key will open a very heavy door.

... when the locked door opens, and there comes in a young woman, deadly pale, and with long fair hair, who glides to the fire, and sits down in the chair we have left there, wringing her hands.