for knowledge of runes, and for power, he sacrificed himself to himself.

Neil Gaiman, Norse Mythology

Consider also:

  1. “Know that herein the Relations between Numbers, though they be mighty in Power and prodigal of Knowledge, are but lesser Things.”
  2. “A curious thing happened on one occasion. At Madura I went into a temple and sacrificed a goat. Soon after I completely cut off my trail by a sea voyage–a great storm was raging, and I was the only person to board the ship. Some time afterwards I returned to India and visited some friends, who knew nothing about my activities in Calcutta. They told me that their servants were excited about a queer tale that I had sacrificed a goat at Madura, the most sacred city of South India.”
  3. “I realized that I had found the key to illimitable knowledge and power, that I had started the path which enabled a man to transcend all the inflictions and disappointments of life.”
  4. “But these are only superficial things. Magic transcends space and time. All things are possible to an adept, but the virtue of his knowledge and power would desert if he used them for selfish ends or personal gain.”
  5. Sandman