Tove Jansson, The Woman Who Borrowed Memories: Selected Stories

"Passion. As you can see, I've lived quite a long time, which is to say I've been working for quite a long time, which is the same thing. And you know what? In the whole silly business, the only thing that really matters is passion. It comes and it goes. At first it just comes to you free of charge, and you don't understand, and you waste it. And then it becomes a thing to nurture."