I think the willfully unimaginative see more monsters. They are often more afraid.

Are — you — insane?” said Hermione in a hushed voice. 'I don't think so,' said Harry, shrugging.

I think they ought to know. You do them a disservice by not confiding something this important to them.” “I didn’t want —” “— to worry or frighten them?” said Dumbledore, surveying Harry over the top of his half-moon spectacles. “Or perhaps, to confess that you yourself are worried and frightened? You need your friends, Harry. As you so rightly said, Sirius would not have wanted you to shut yourself away.

For a split second, Harry thought how absurd it was for Tonks to expect the dummy to hear her talking that quietly through a sheet of glass, when there were buses rumbling along behind her and all the racket of street full of shoppers. Then he reminded himself that dummies could not hear anyway.

Merlin’s beard, Harry, you made me jump,” said Slughorn, stopping dead in his tracks and looking wary. “How did you get out of the castle?” “I think Filch must’ve forgotten to lock the doors,” said Harry cheerfully, and was delighted to see Slughorn scowl.

In the end, it mattered not that you could not close your mind. It was your heart that saved you.

He's only silent because he's too thick to string two words together.