The first few chapters of the book deal largely with explaining Fort's thesis. As a particular instance, he cites the strange glowing in the sky worldwide which supposedly resulted from the 1883 eruption of the volcano Krakatoa. Fort claims that such phenomenon had in fact preceded the eruption by several months, and suggests that scientists, who had been puzzled by the phenomenon initially, used Krakatoa as a convenient explanation for something that they could not explain previously.