Why did the poet throw the log at the snake?
On realising that the snake was about to recede as he turned his back, the poet hit him with a log in protest. The snake had mesmerised the poet with his beauty and so the poet did not want him to return to "that horrid black hole."
The poet at first admired the snake, but when his education overpowered his instinct, he concluded that a snake is a dangerous creature which has to be killed in order to prevent a potential attack in the future. He therefore threw a log at the snake.