that way madness lies

== English == === Alternative forms === that way lies madness === Etymology === From The Tragedy of King Lear (c. 1606), see quotations. === Phrase === that way madness lies (hyperbolic) The mentioned activity, line of inquiry, etc., should not be pursued because it will cause frustration, anger, etc., and lead to no good. === Further reading === Gary Martin (1997–), “That way madness lies”, in The Phrase Finder.