Students at Hogwarts are taught how to use spells, the correct incantation, pronunciation, tone of voice, wand action/movement, thought etc.

However Harry, who simply read the name of it in the Half-Blood Prince's Potions book, manages to produce the spell with no prior knowledge of how.

How does he know how to use Sectumsempra?

1 Answer 1


It would appear that the spell is an incantation (e.g. When you say it, it casts the spell). When it's cast, it simply follows the line of the wand rather than requiring any specific wand movement.

Harry ignored her. He had just found an incantation (Sectumsempra!) scrawled in a margin above the intriguing words ‘For Enemies’, and was itching to try it out, but thought it best not to in front of Hermione. Instead, he surreptitiously folded down the corner of the page.

Harry Potter and the Half-Blood Prince


‘SECTUMSEMPRA!’ bellowed Harry from the floor, waving his wand wildly.
Blood spurted from Malfoy’s face and chest as though he had been slashed with an invisible sword. He staggered backwards and collapsed on to the waterlogged floor with a great splash, his wand falling from his limp right hand.

Harry Potter and the Half-Blood Prince


A few of them stumbled, one or two of them bound in ropes, but those climbing on to the rock behind them merely stepped over or on the fallen bodies. Still slashing at the air with his wand, Harry yelled, ‘Sectumsempra! SECTUMSEMPRA!’

Harry Potter and the Half-Blood Prince

  • 1
    Is there any proof that an incantation can simply be said without anything else needed? I know we don't like the HP Wikia but it says on this link harrypotter.wikia.com/wiki/Incantation that 'An incantation will not work without the conscious effort of magical power and the possession of the proper skill and intent.'
    – user82081
    Apr 20, 2017 at 16:32
  • I was actually typing up a similar answer. All that Harry does was read the spell out of the book. When the incantation is the most important thing, just saying it should work. Some spells don't seem to require specific wand movements. As far as how Harry knew how to pronounce it, it's a fairly easy pronunciation to figure out. Most of the spells follow the same sort of phonetic rules. People reading them can easily figure out at least a general idea of how to say them. Even if they don't say it quite right, it should be right enough to have an effect.
    – Obsidia
    Apr 20, 2017 at 16:37
  • 2
    @Bellatrix 'Most of the spells follow the same sort of phonetic rules.' Except 'Leviosa'! ;)
    – user82081
    Apr 21, 2017 at 9:11
  • 1
    @user82081 Leviose would not be a incantation, as they clearly have to practice wand movements in order to produce the spell ...
    – Rubenxfd
    Sep 8, 2017 at 10:09
  • 1
    It seems that your answer is that there is a separate category of magic called “incantations” which doesn’t require specific wand movements. I don’t think this is correct. The term incantation is used as a general reference to the spoken words of a spell. Wingardium Leviosa is explicitly described in Order of the Phoenix as having both an incantation and a specific wand movement.
    – Alex
    Dec 17, 2019 at 13:21

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