Dumbledore shook his head.

'Curiosity is not a sin', he said. 'But we should exercise caution with our curiosity… yes indeed…'

Frowning slightly, he prodded the thought within the basin with the tip of his wand. Instantly, a figure rose out of it, a plump, scowling girl of around sixteen, who began to revolve slowly, with her feet still in the basin. She took no notice whatsoever of Harry or Professor Dumbledore. When she spoke, her voice echoed as Snape's had done, as though it was coming from the depths of the stone basin: 'He put a hex on me, Professor Dumbledore, and I was only teasing him, sir, I only said I'd seen him kissing Florence behind the greenhouses last Thursday…'

'But why Bertha,' said Dumbledore sadly, looking up at the now silently revolving girl, 'why did you have to follow him in the first place?'

'Bertha?' Harry whispered, looking up at her. 'Is that - was that Bertha Jorkins?'

'Yes,' said Dumbledore, prodding the thoughts in the basin again; Bertha sank back into them, and they became silvery and opaque once more. 'That was Bertha as I remember her at school.'

The silvery light from the Pensieve illuminated Dumbledore's face, and it struck Harry suddenly how very old he was looking. He knew, of course, that Dumbledore was getting on in years, but somehow he never really thought of Dumbledore as an old man.