What does Robert M. Pirsig's "Quality" correspond to in Buddhism?

The concept of "Quality" relates to the direct experience of the moment, as described in the book *Zen and the Art of Motorcycle Maintenance*. I was wondering if this has a parallel in Buddhism? To me, the idea of Quality seems to be like Sunyata turned inside-out. Here is a quote from the book: > Quality ... you know what it is, yet you don't know what it is. But > that's self-contradictory. But some things are better than others, > that is, they have more quality. But when you try to say what the > quality is, apart from the things that have it, it all goes poof! > There's nothing to talk about. But if you can't say what Quality is, > how do you know what it is, or how do you know that it even exists? If > no one knows what it is, then for all practical purposes it doesn't > exist at all. But for all practical purposes it really does exist. What would we call this idea?