Final answer:
The speaker in the given quote is Satan from John Milton's 'Paradise Lost'. It describes his first experience of pain and convulsion as a result of his rebellion against God.
Step-by-step explanation:
The speaker in the given quote is Satan. This quote is from John Milton's epic poem 'Paradise Lost', which tells the story of Lucifer's fall from heaven and his transformation into Satan. The line refers to the moment when Satan first experiences pain and convulses in agony. This demonstrates the physical and emotional suffering Satan endures as a consequence of his rebellion against God.