How do I understand explicitly the meaning of this last sentence from the fourth letter of Frankenstein? Why would the ship be "wrecked" when it was not? Also, how do I account for the usage of em dash followed by "thus"?
Even now, as I commence my task, his full-toned voice swells in my ears; his lustrous eyes dwell on me with all their melancholy sweetness; I see his thin hand raised in animation, while the lineaments of his face are irradiated by the soul within. Strange and harrowing must be his story, frightful the storm which embraced the gallant vessel on its course and wrecked it—thus!
-- Frankenstein, Mary Shelley