Answer:
The central idea of the excerpt is that London will once again thrive despite the calamities that befell it.
Step-by-step explanation:
John Dryden talks about all the social, political, and territorial tragedies that had happened upon London, but he also gives the people hope of its recovery in this lines, as he expresses himself about her as a person, not a city, this gives it the soul, heart, and character to survive to any kind of inconvenience and setbacks.