All that glitters is not gold.

Literally this means

                   for all x, if x glitters, then x is NOT gold

which is silly since gold glitters and... is gold.

They meant to say

                  there exists x, x glitter and x is not gold

or maybe they want to say most things that glitter are not gold:

                  for all but a finite number of x if x glitters then x is not gold.