A miscellany of historical sketches examines episodes of mass delusion and collective behaviour, ranging from speculative financial manias to superstitious and pseudoscientific fads. It surveys economic bubbles such as the Mississippi and South-Sea schemes and tulip mania, and treats pursuits like alchemy, prophecies, fortune-telling, and mesmerism, together with social panics including witch-hunts, duelling, relic-worship, haunted houses, poisoning scandals, and popular fascination with criminals. Chapters combine narrative anecdotes, contemporary caricatures, and commentary to reveal recurring patterns in how enthusiasm, fear, and credulity spread through communities and eventually peak and collapse.