Prov. Foolish people usually do not understand when a situation is dangerous, so they are not afraid to do things that would frighten more sensible people. Alan: Bob is too scared to go in and confront the boss, so I'm going to. Jane: Fools rush in where angels fear to tread.
Ignorant or inexperienced individuals get involved in situations that wiser persons would avoid, as in I've never heard this symphony and here I am conducting it-oh well, fools rush in where angels fear to tread , or He tried to mediate their unending argument-fools rush in. This expression, so well known it is sometimes shortened as in the second example, is a quotation from Alexander Pope's Essay on Criticism (1709): "No place so sacred from such fops is barr'd ... Nay, fly to altars; there they'll talk you dead; For fools rush in where angels fear to tread."