An explanation

Since reading Cutting for Stone, as I said in the post below, I've not really understood the reference. Rachel who read the book too was also mystified and she was ambitious enough to do some research which I quote:

Human beings have known of bladder stones ("vesical calculi") for thousands of years, and have attempted to treat them for almost as long. The oldest bladder stone that has been found was discovered in Egypt around 1900, and it has been dated to 4900 BC. The earliest written records describing bladder stones date to before the time of Hippocrates (ca. 460-370 BC). However, lithotomy was a fairly common procedure in the past, and there were specialized lithotomists. The ancient Greek Hippocratic Oath includes the phrase: "I will not cut for stone, even for the patients in whom the disease is manifest; I will leave this operation to be performed by practitioners," a clear warning for physicians against the "cutting" of persons "laboring under the stone"; an act that was better left to surgeons (who were distinct from physicians at that time in history). Operations to remove bladder stones via the perineum, like other surgery before the invention of anesthesia, were intensely painful for the patient.[1]

In short, it is surgeons who do the really hard work of "cutting for stone." Since the pivotal characters in the novel are all surgeons of one type or another and many difficult [and blood] surgeries are described in the book, and the surgeons happen to be very skilled, they are the ones who must "cut for stone." A pun is involved as well, as Stone is the last name of the protagonist and his twin brother and, of course, their father.

I am appropriately humbled because I was too lazy to do the research myself -- in our Google-era such research is so easy not to do it is indeed lazy. In an earlier time ignorance about these "minor" but curious things might be excusable but it no longer is. i think I've just learned a les