It is a bit of a leap, but quite possibly an oblique reference to Voltaire's Candide. He spent some time dismantling the idea that this was the best of all poss

It is a bit of a leap, but quite possibly an oblique reference to Voltaire's Candide. He spent some time dismantling the idea that this was the best of all possible worlds (the phrase apparently started with Leibniz) and the Lisbon earthquake featured prominently.