How is Satan's speech in book 4 lines 32-113 help the theme of the story as a whole?

Satan's speech in Book IV, Lines 32-133, supports the theme of the story because in this speech, Satan speaks to his own Fall. He speaks of his wn pride and ambition, the loss of Heaven, the matchless King (God), who did not receive the treatment he received from His own creation. Satan speaks of his infinite despair and misery..... he wishes he could repent and return to his former state. This speech relays the same message as Paradise Lost..... he lost his paradise through choice, free will, and vanity, in the same way Adam and Eve would lose their own.