How did he know?

[justcarol67]

No: HPFGUIDX 146915

KJ wrote:
> 
>       I'm thinking that Grindelwald had something to do with
Riddle's  education. I don't think that he made his first horcrux
until after he  left school. JKR said that Grindelwald's death was
important and he is  listed as having died in 1945, the year Riddle
graduated. We do know that he had made at least one horcrux while
working at B&B. He was  trying to get someone to tell him how to do it
while at Hogwarts.

Carol adds:
While we don't know for sure that TR didn't make any Horcruxes while
he was still at school, I tend to think that KJ is correct; he found
out how to do it from Grindelwald before 1945, his last year (or
half-year) at school. His graduation (or whatever the British term is)
and the defeat of Grindelwald in the same year is probably not
coincidence.

TR had written the diary (and preserved his own memory in it) before
he left for the summer holiday after his fifth year, but it wasn't yet
a Horcrux because, as the Slughorn memory (which seems to take place
during his sixth year) shows, he didn't yet know how to make one. He
managed to kill his parents and grandparents and to take Morfin
Gaunt's ring the summer after his fifth year, but as the diary memory
shows, he was still only sixteen and had to return to the Muggle
orphanage. If he hadn't his disappearance would almost certainly have
been investigated. But in the summer between his sixth and seventh
years, he was seventeen and free to do as he liked. That would have
been the perfect time to visit Grindelwald and learn what he needed to
know. If so, he could have made the first two Horcruxes while he was
still at school. He did not, however, leave them there. He kept the
diary, which he eventually placed in Lucius Malfoy's possession
(Lucius was not yet born at this time) and he hid the ring in the
Gaunts' hovel.

As the change in his appearance at that point indicates, he had made
at least one of those two Horcruxes when he obtained the cup and
locket for additional Horcruxes and added the murder of Hepzibah Smith
to his resume. At that time, he had been out of school only a few
years, and, IIRC, he went to work at B and B immediately after
graduation in the very year that Grindelwald was defeated. We don't
know which month GW was defeated in or how much later he actually died
(JKR says that he *is* dead). But I'm guessing that TR had already
visited him and learned what he needed to know in the summer of 1944.

I very much doubt that TR could have learned to create a Horcrux at
Hogwarts using the restricted section of the library or by using
Legilimency on Slughorn, as someone on this list suggested. Even if he
could read or hear the incantation in Slughorn's mind, and we haven't
seen Legilimency work that way (it seems to be primarily visual), I
don't think he would know how to *work* the spell. Slughorn claims not
to know the incantation, and surely something more than a simple
incantation would be required to first remove the soul bit and then to
encase it in an object.

Not sure where I'm going with this, just that during the summer
between his sixth and seventh years (July and August 1944) would have
been the perfect time to visit Grindelwald, both because TR was
finally of age and because GW was alive and undefeated at that time.

Carol, who thinks that Legilimency doesn't reveal everything the
Legilimens wants to know, only what's uppermost in the mind of the
person being Legilimensed, and that the Legilimens can turn it on and
off; he doesn't use it all the time.