"From this point forth, we shall be leaving the firm foundation of fact and journeying together through the murky marshes of memory into thickets of wildest guesswork. From here on in, Harry, I may be as woefully wrong as Humphrey Belcher, who believed the time was ripe for a cheese cauldron."
-- Albus Dumbledore
On the way to Dumbledore’s office, Harry avoids Professor Trelawney, who has been drinking and is interpreting what a set of playing cards indicate about the future.
They view Bob Ogden’s memory of the Gaunt house, and discuss the circumstances surrounding Voldemort’s birth. Harry asks for and receives permission to tell Ron and Hermione about the lesson, but Dumbledore tells Harry not to tell anyone else.
The exact date is uncertain, but we know that this lesson is the Saturday immediately following the first day of classes (HBP9), so it is most likely September 7.
When the village of Little Hangleton comes into view in Bob Ogden's memory, the town's church and graveyard appear to be particularly conspicuous to Harry. Perhaps Harry picked out the graveyard because he was transported there at the end of his fourth year. -BB
Marvolo claims believes that his ring bears the Peverell family's coat of arms, but the symbol on the ring is actually the Deathly Hallows symbol.
The spell Morfin Gaunt uses on Bob Ogden may be the Curse of the Bogeys or a related spell. The spell's effects are similar to the effects of the Curse of the Bogeys, which causes massive amounts of mucus to issue from the nose. However, the "goo" coming from Bob Ogden's nose appears - at least to Harry - to be some kind of pus, rather than mucus. -BB