"The hardest bones, containing the richest marrow, can be con..." — Franz Kafka quote meaning

The hardest bones, containing the richest marrow, can be conquered only by a united crushing of all the teeth of all dogs. That of course is only a figure of speech and exaggerated; if all teeth were but ready they would not need even to bite, the bones would crack themselves and the marrow would be freely accessible to the feeblest of dogs. If I remain faithful to this metaphor, then the goal of my aims, my questions, my inquiries, appears monstrous, it is true. For I want to compel all dogs thus to assemble together, I want the bones to crack open under the pressure of their collective preparedness, and then I want to dismiss them to the ordinary life they love, while all by myself, quite alone, I lap up the marrow. That sounds monstrous, almost as if I wanted to feed on the marrow, not merely of bone, but of the whole canine race itself. But it is only a metaphor. The marrow that I am discussing here is no food; on the contrary, it is a poison.