When you go to your doctor for a physical, he thumps you, feels you for swelling, and otherwise pokes and prods.  Like a policeman searching for a thief, he’s looking for anything that can cause you trouble.  And if he finds anything that seems irregular, he wants to check it out.  When I had a physical a few years ago, the doctor found a tiny lump near my collarbone.  “Hum!” he said in that not-so comforting doctor tone, “we had better check this out.”  He did, too.  He wanted a biopsy—a tiny bit of flesh (my flesh, of course), which could be put under a microscope and examined.  He explained that he would numb the spot and use a needle to get to the heart of the problem.