Original sentence: This forms a contradiction  because he uses the words of a Cretan (always liar) in order to prove that Cretans are always liars, also concluding that Epimenides (a Cretan) had surely told the truth (that Cretans are always liers)
Edited sentence: This forms a contradiction  because he uses the words of a Cretan (always a liar) in order to prove that Cretans are always liars, also concluding that Epimenides (a Cretan) had surely told the truth (that Cretans are always liars)