"It's all about how much of your will you put into it. If you want something strong, you need to play that way. Focus on what you want and put that energy into the song you play. The more you control your will, the better your control over what you summon."

He hasn't ever really had to explain this before..It took him months to figure out how to use the dark cultivation and Aziraphale only has the ability for probably a few days. It's a lot like flying in that way..trying to learn a lot in a short period isn't the easiest of things to do.