The poet experiences feelings of self-derision, guilt and regret after hitting that snake. He feels so because he tried to harm a guest and a harmless creature. The expressions which show such feelings are:
(i) ‘And immediately, I regretted it’
(ii) ‘I thought how paltry, how vulgar, what a mean act!’
(iii) ‘I despised myself and the voices of my accursed human education’
(iv)‘And I have something to expiate—A pettiness’
