When did Snape invent his curses?

[Deb]

No: HPFGUIDX 134517

--- In HPforGrownups at yahoogroups.com, "lapland874" <lapland874 at y...> 
wrote:
> Snape had apparently invented several curses as evidenced by the 
potion 
> book which Harry used all year.  However one curse was actually used 
> the previous year.  When James turned Snape upside down was on the 
day 
> of his OWL's exam.  The advanced potions book was not used by Snape 
> until the following year.  Unless he was already using it?  So did 
> Snape invent that curse/jinx or did he just figure it out and then 
> write it in the book?  Obviously some of them where truely his, but 
> maybe not all of them.
> 
> 
> Lapland874

 It is possible he invented the Levicorpus spell and the Sectumsempra 
spell himself .... however it is also possible that he knew them when 
he came to Hogwarts.
  (from Gof) "I think they've both got a point," said Sirius, looking 
thoughtfully at Ron and Hermione. "Ever since I found out Snape was 
teaching here, I've wondered why Dumbledore hired him. Snape's always 
been fascinated by the Dark Arts, he was famous for it at school. 
Slimy, oily, greasy-haired kid, he was," Sirius added, and Harry and 
Ron grinned at each other. "Snape knew more curses when he arrived at 
school than half the kids in seventh year, and he was part of a gang 
of Slytherins who nearly all turned out to be Death Eaters."

 The most prevelent (from what I've read so far) theory on the potions 
text book is that it had once belonged to SS's mother. We do not know 
for sure that the writing in the book ... or all of the writing in the 
book... is Severus's... some could be his mother's ... or from who 
ever was the previous owner. Harry learns the book was printed 50 
years prior to it coming into his hands.... there for printed in 1946. 
So it could not have been Tom Riddle's book as he left school in 1945. 
It could indeed have been Snapes's mother if she was in her 6th year 
at Hogwarts in 1946 ... which would make her about age 30 when SS is 
born. So his mother could have know Tom Riddle while she was at 
school. I wonder if she was in Slytherin when she attended Hogwarts? 
If she did know Tom and had herself been interested in the Dark Arts 
it is possible she passed on some of her knowledge to Snape before he 
went to school.  

Deb (relative newbie poster to this site... but I've been lurking and 
enjoying the intelligent conversation  for quite a while)