A dog stumbles across a bone that has been exposed to the elements for many months, and is therefore bleached of any residual flesh or marrow. The dog gnaws on it for some time before he finally determines that he is "not finding" any satisfaction in the bone, and he thus turns away from it in disgust. It is not that the bone is intrinsically disgusting; it is rather the case that the dog's raging desire for meat just will not be satisfied by the bone . . . when he wakes up to the truth that the bone is empty of anything that will offer him satisfaction, he becomes disenchanted, and spits it out in disgust.

Buddhist Teaching Story , The Wisdom of Yoga by Stephen Cope