The wealth of ambiguity

When we read these lines by Robert Burns (1759-1796),

     Oh my luv is like a red, red rose,
     That's newly sprung in June . . .
    
we don't know whether he compares a woman he loves to a flower or whether it is his own emotion he describes.  And the multiplicity of meanings is a good and pleasing thing.  Similarly, when we read the problem,

     Solve the equation, x² + 4 = 0