Context:

Tom explicitly mentions this as the book they are discussing in the episode. He says he read it on a holiday in Greece about three or four years ago. The book argues that climate and disease played a major role in the fall of the Roman Empire.

Context:

Referenced multiple times in the discussion as the traditional model for understanding Rome's decline. Mentioned as 'the old kind of Edward Gibbon decline and fall sort of model' and later referenced when discussing Gibbon's view that the Antonine Age was 'the happiest in human history.'