Amos only fell in because he was dancing on the grave. Seems like he'd known the dead guy and when he stumbled across his grave he (Amos) was so happy he had to do a totentanz. I explained to Mom that it wasn't Amos's fault that the coffin had decayed and Amos was effectively dancing on air (or sort of air). You shouldn't bring it up again because Mom was very understanding and even gave Amos some cookies and milk.