Cathy Wright takes up case 8 in The Gateless Barrier:

Master Gettan said to a monk: “Keichu made a cart whose wheels had a hundred spokes. Take both front and rear parts away and remove the axle: then what will it be?”

Cathy comments:

We work on a koan until we are out of answers, and then the koan begins to work on us; and the question “What will it be?” springs forth the way a fox springs from a bush.