He let me approach him and grasp the icky thing. It was a long strand of leather he likes to play with. He had been eating it like spaghetti, from one end, and over half of it was deep in his tummy. I grasped the slimy end protruding from his mouth and gently pulled it out. Then I got a cloth to wipe his chin. He complained, but let me do it.
He seems all right now, but I'll keep an eye on him. Surely, if he had gotten that whole mass into his tummy, it would have killed him. As it is, so long as he hasn't chewed off any pieces of it, there's nothing in him to cause him any further distress (though I found a piece downstairs on the floor that he had chewed off in his playing with it).
So, I'm giving thanks to God for finding him in time, and asking you all for prayers for Cuthbert that he takes no further harm from this. Now, I think I'll see if I can find any kitty laxative to give him, just for good measure.