Why didn't Lily have to die?

[greatelderone]

No: HPFGUIDX 93718

--- In HPforGrownups at yahoogroups.com, "justcarol67" 
<justcarol67 at y...> wrote:
> I don't think Voldemort's intentions matter. Certainly if he had
> killed Harry and then killed Lily, her death would not have been a
> sacrifice, regardless of his intentions. It would only have been a
> second murder. But IMO it's Lily's intentions that matter. It's her
> death that saves her son and her deliberate giving of her life that
> makes her death a sacrifice.

I diagree here. A sacrifice entails that you give up something 
inexchange for something of greater, equal or less value . Her 
getting scrapped next by Voldemort wouldn't have qualified her act as 
a sacrifice. 

Besides if we take this to the logical conclusion and assume that 
most mothers are as willing to die for their children, that AV is 
used frequently for murders and that wizard wars like what Voldemort 
waged were like every 50 year events then wouldn't it be common 
enough for Voldemort to have kept this charm in mind?