The poet experiences feelings of self-derison, guilt and regret after throwing a log of wood at the snake. The snake had come there to quench his thirst and seek his hospitality. The poet acts in a senseless fit of anger. He realises that his act is ‘vulgar’ and mean. He realises that he has ‘something to expiate’. It is his ‘pettiness’ that made him throw a log at the snake and he must atone for it.