Blish began his Cities in Flight series in the early 1950s, a period of enormous national paranoia. Fear of the Red Menace was at its height, the House Un-American Activities Committee (HUAC) was working hard to cow the intelligentsia of the United States into passivity, and Senator Joseph McCarthy of Wisconsin was at the pinnacle of his notoriety, destroying careers, threatening any day to disclose the hundreds of communists supposedly working in the federal government. Many liberal science fiction writers of the period reacted to this political atmosphere by writing stories set in futures which were logical extensions of the Cold War period, and Blish's Cities in Flight series is an example of this trend. Using concepts borrowed (not always accurately) from the philosopher Oswald Spengler, the author of The Decline of the West (1923), Blish described a future America on the verge of collapse, sunk into...