Incantations vs. spells

[potioncat]

No: HPFGUIDX 97336

snipping first portion
Arya:
> 
> Now, if you were to ask if an incantation is NEEDED to cast a 
spell, then I 
> think the answer is no--the incantation is a way to hel 
pmemorisation and 
> focus.  Dolohov shows that he can indeed cast without shouting out 
a curse.  
> We here Snape mutter his incantations all the time and we see 
several 
> porofessors tap their wands to set off a spell without any words at 
all.  
> 
>

Potioncat:
I agree that incantation can be as short as one word, or a sustained 
muttering or long poem to be put to music and sung with frogs or 
toads ;-)

It is important to speak clearly as we were warned via Baruffio and 
that was obvious with Neville.  But why Dolohov could do magic when 
he was silence, I do not know.  And yes, we have read passages where 
the wand is mentioned but speaking isn't or seen magic done with the 
snap of a finger. Maybe whether the incantation is needed depends on 
the magic itself, or the power of the wizard casting it.

Someone did quote the "no silly incantations" line in a different 
post.  Is is that in the book or just in the movie? 

Potioncat