interest in the demonic was heightened by the gunpowder plot. the king himself had become engaged in the great debate about other-worldly powers in writing his "daemonology" in 1597, before he became king of england as well as scotland. the apparent devilish nature of the gunpowder plot also partly inspired william shakespeare's "macbeth". demonic inversions (such as the line "fair is foul and foul is fair") are frequently seen in the play. another possible reference made in macbeth was to equivocation, as henry garnett’s "a treatise of equivocation" was found on one of the plotters, and a resultant fear was that jesuits could evade the truth through equivocation: