system
Given the following post, respond as if you're commenting on Reddit:
human
[Harry Potter] Was Lily Potter's "Sacrificial love spell" a previously undiscovered enchantment? Are willing sacrifices the cornerstone of any other great and powerful spells?

Voldemort believed something as superstitious as a sooth-sayer's prophecy, shouldn't he at least be aware of the magic attributed to a mother's love? Surely Lily Potter couldn't be the first woman to sacrifice herself to protect a child, right? Are there any historical examples of this in the wizarding world?

On a different note... Is there any evidence that a botched memory wipe is the cause of Professor Trelawney's eccentricities?
gpt
Willing sacrifices (though usually not of your own life) are indeed the cornerstones of some powerful spells.  There were a lot of factors that led up to what happened that night.  
1. Voldemort promised Snape he would spare Lily.  While there was no unbreakable vow, it did carry some magic weight.  
2. Lily had an easy out.  She sacrificed her life, not just putting herself in danger by fighting for him, but flat out laying down her life essentially for no reason.  
3. Voldemort was in the process of making a horcrux, not just a regular murder.  
4. There was a magical prophecy about Harry being the one to kill Voldemort.  
  
While any one or two of these factors is bound to have happened throughout history, all 4 coming together probably hasn't, or at the very least is extremely uncommon.