The elements of London that Johnson brings out in his poem are reflective of the rise of commerce. The London that Johnson describes is not quaint and small. Rather, it is the realization of mercantilist expansion and commercial enterprise. For Johnson, the metropolis of London is a reminder that with mercantile expansion comes realities that cause one to inevitably mourn.
Thales's reasons for leaving London represent the logical extensions of mercantilist expansion. The vision of London from which Thales departs is a reality where mercantilist expansion and economic progress have supplanted human connection and values:
There none are swept by sudden Fate away,
But all whom Hunger spares, with Age decay:
Here Malice, Rapine, Accident, conspire,
And now a Rabble Rages, now a Fire;
Their Ambush here relentless Ruffians lay,
And here the fell Attorney prowls for Prey;
Here falling Houses thunder on your Head,
And here a female Atheist talks you dead.
The collusion between elements like "Malice, Rapine" and "Accident" are realities of mercantilist expansion. The predatory nature of commercial expansion is evident in the "Attorney" who "prowls for Prey." The overcrowding that is intrinsic to mercantilist growth is evident the "falling Houses" that "thunder on your head." The worship of wealth as the only religion has supplanted the divine, and Johnson points to this reality reflected in the rise of atheism. There is little in way of "dissipated wealth," rather it is consolidated in the hands of the few at the costs of the many.
The condition of England's glorious past is something that Johnson argues had given way to the realities of commercial growth. The present that Thales sees is one where mercantile expansion lies at the heart of everything in modern England:
Behold her Cross triumphant on the Main,
The Guard of Commerce, and the Dread of Spain,
Ere Masquerades debauch'd, Excise oppress'd,
Or English Honour grew a standing Jest.
The "jest" is that there could be anything other than "the Guard of Commerce" in modern England and in London, in particular. The world of London is one where all actions are based upon the desire to expand economic frames of reference through devotion to "Vice and Gain." The honorable individual stands no chance of success in a world where material profit and mercantile expansion dominates over all. In the end, Johnson's poem represents why the individual has little other choice but to retire to a realm away from the terrors of mercantilist expansion and the corruption within material pursuits of the good.