Board Thread:General Discussion/@comment-26179634-20141219181118/@comment-4975807-20160408175908

Perhaps the brain ingredient required was not actually an actual brain, but a magical representation of it, in order for the time spell to work? Though that seems too convenient of a way to explain why Mr. Gold's actual brain wasn't used. Out of all the spell ingredients, Regina's heart was the most literal of them because her actual heart was used. But the three other ingredients; symbols of courage (David's sword after he fought his greatest fear), innocence (baby Neal) and wisdom (Mr. Gold's spun gold turned into a brain??) were representations of things.