Final answer:
Shelley's prophecies typically involve revolutionary change or the downfall of corrupt institutions, reflecting his radical views during the time of the Industrial Revolution and political unrest in 19th-century Britain. Without the specific lines, we can only generalize based on the themes common in his work.
Step-by-step explanation:
In England in 1819, Percy Bysshe Shelley gives a scathing critique of early 19th-century British society. Lines 69 and 70 from a given poem are not directly provided in the information above, but Shelley's work often includes prophecies about the future, typically involving revolutionary change or the downfall of corrupt institutions. In the context of his writing and life, any prophecy likely pertains to the hope of transformation arising from the ashes of a deeply flawed society. His usage of metaphors is vivid, equating rulers to aged and diseased individuals and institutions to parasitic entities, all contributing to the distress and oppression of the common people.
Unfortunately, without the specific text of lines 69 and 70, it's not possible to provide a commentary on exactly what Shelley prophesies in these lines. However, knowing Shelley's body of work and radical outlook, the prophecy would probably be in line with his revolutionary aspirations against the background of the Industrial Revolution, political unrest, and the socio-economic issues of the time.