The reference is to Benjamin’s famous figure of the angel of history:
His face is turned toward the past. Where we perceive a chain of events, he sees one single catastrophe which keeps piling wreckage upon wreckage and hurls it in front of his feet. The angel would like to stay, awaken the dead, and make whole what has been smashed. But a storm is blowing from Paradise; it has got caught in his wings with such violence that the angel can no longer close them. The storm irresistibly propels him into the future to which his back is turned, while the pile of debris before him grows skyward. This storm is what we call progress.
Victor was also flatulent; when he farted Alex and I joked that the storm was blowing out of Paradise. It was just a stupid joke, an ongoing stupid joke with its inevitable equally stupid variations, but there was something to it: the blown-backwards angel was an apt figure for Victor, who got more involved in the storm of progress than anyone I knew in San Francisco. And having seen what the storm of progress can do to a person, a city, a world, I am disposed to believe that Paradise’s wind smells like intestinal gas more than it does like anything sweet or good.