"Ah, but lights and candles work on the same principles every time, correct?" Liliana said. "And work the same way for everybody. But magic certainly doesn't do so. Even if you took two black-aspected Planeswalkers, we wouldn't cast magic the same way, even though we're using the same mana to do so, our spells would be different, and a white mana user and someone without the spark at all wouldn't be able to do anything at all."