The Old Magic:
Magic of a Most Powerful Sort
The old magic, also referred to as ancient magic, is magic which is not cast by wizards with wands. It is part of the "magical-ness" of the universe. There are a number of examples:
"For he has been better protected than I think even he knows, protected in ways devised by Dumbledore long ago, when it fell to him to arrange the boy's future. Dumbledore invoked an ancient magic, to ensure the boy's protection as long as he is in his relations' care. Not even I can touch him there." (Voldemort, GF33)
Lily's sacrifice of herself for Harry created a protection Voldemort could not break through. In fact, the sacrifice infused his skin with that love and Voldemort and Quirrell when under Voldemort's control couldn't even touch him.
When one wizard saves another wizard's life, it creates a certain bond between them, a "life debt." James Potter saved Snape's life many years ago, but the effects of it still influence Snape's life. Harry spared the life of Peter Pettigrew, with consequences we have yet to see played out. Certainly Pettigrew's hesitant suggestions to Voldemort that they find an alternate victim for his rebirth spell came from Pettigrew's sense of life debt to Harry.
- "Dragons are extremely difficult to slay, owing to the ancient magic that imbues their thick hides, which none but the most powerful spells can penetrate." (GF20)
"Pettigrew owes his life to you. You have sent Voldemort a deputy who is in your debt...When one wizard saves another wizard's life, it creates a certain bond between them... and I'm much mistaken if Voldemort wants his servant in the debt of Harry Potter."
"I don't want a connection with Pettigrew!" said Harry. "He betrayed my parents!"
"This is magic at its deepest, its most impenetrable, Harry. But trust me... the time may come when you will be very glad you saved Pettigrew's life." (PA22)