I know a lot of ancient languages have been deciphered by finding something to compare to, like the Rosetta stone, or the Behistun inscription for cuneiform, but what about ancient languages with nothing to compare to? Specifically really i'm fascinated by the inability of anyone thus-far to translate Linear A, and am wondering how linguists, archaeologists or others are working to translate it. What is the method, and why has translation eluded those working on it?