Exuberance can veer sharply into disturbing territory . . . Enthusiasm shares a border with fanaticism, and joy with hysteria; exuberance lives in uncomfortable proximity to mania. . . . Unchecked, enthusiasm runs roughshod over reason and intrudes into the private emotional territory of others, imposing, as it goes, its own energy and tempo.
— Kay Redfield Jamison, Exuberance