Voldemort percebeu o perigo em deixar Harry ler sua mente - Harry estava recebendo muita informação sobre o que Voldemort estava fazendo, pensando e sentindo naquele momento.
"So tell me, Harry," said Dumbledore. "Your scar...has it been hurting at all?"
Harry raised a hand unconsciously to his forehead and rubbed the lightning-shaped mark. "No," he said, "and I've been wondering about that. I thought it would be burning all the time now Voldemort's getting so powerful again."
He glanced up at Dumbledore and saw that he was wearing a satisfied expression.
"I, on the other hand, thought otherwise," said Dumbledore. "Lord Voldemort has finally realised the dangerous access to his thoughts and feelings you have been enjoying. It appears he is now employing Occlumency against you."
Isso precede os eventos da OotP, onde por causa dessa "brecha da leitura da mente", Harry é capaz de salvar Arthur Weasley e revelar o aparente interesse de Voldemort no Departamento de Mistérios.