Dumbledore found it rather amusing that Horace had disguised himself as an armchair in an attempt to fool him.
If the visitor had been a Death Eater, Horace's strategy might actually have worked.
Unfortunately, the odds of a Death Eater coming to see Horace in the middle of the night were truly low, and even Horace himself knew that.
Dumbledore was not surprised that Harry had successfully persuaded Slughorn to return to Hogwarts to teach. His old friend clearly would not pass up the chance to add The Boy Who Lived to his collection.
Besides, for an old man who wanted a peaceful life, constantly moving from place to place was far too exhausting.
Once Horace had agreed to teach at Hogwarts, half of Dumbledore's plan had succeeded. Getting the number of Horcruxes Voldemort had made out of Horace would merely be a matter of time.
As for the number of Horcruxes Albert had predicted, Dumbledore was actually willing to believe it. But he could not take risks because of that; he still needed to obtain that memory from Horace and confirm it again.
He trusted Harry would complete the task admirably.
The Horcruxes already destroyed were the Diadem, the diary, and a venomous snake. That meant there might only be the last three Horcruxes and Voldemort's main soul left.
As for the fragment in Harry's forehead, Dumbledore had already made arrangements.
As long as he destroyed the ring and found the Horcrux Albert had foretold, they would truly be only one step away from utterly eliminating Voldemort.
Dumbledore had never felt so optimistic about the future.
He once again relived Bob Ogden's memory through the Pensieve. This was not the first time Dumbledore had done so; since obtaining the memory, he had long forgotten how many times he had