Sentence:  It is tempting to speculate about the incentives or compulsions that might explain why anyone would take to the skies in [the] basket [of a balloon]:nb...; perhaps to moralise on the oneness or fragility of the <WSD>planet</WSD>, or to see humanity for the small and circumscribed thing that it is;nb.... 
Meaning of the word marked with <WSD> tags:  In phrases such as "the planet", "this planet", sometimes refers to the Earth.